RECITALS
Whereas, in accordance with article 46, paragraph I, of the Federal Law on Metrology and Standardisation, the Ministry of Labour and Social Welfare submitted to the National Advisory Committee for Standardisation on Occupational Safety and Health, at its Seventh Ordinary Session, held on 12 August 2014, the preliminary draft of Official Mexican Standard PROY-NOM-033-STPS-2014, Safety conditions for work in confined spaces, and that Committee found it to be appropriate and agreed that it should be published as a Draft in the Official Gazette of the Federation; Whereas, as determined by articles 69-E and 69-H of the Federal Law on Administrative Procedure, the corresponding Draft was submitted for consideration to the Federal Commission for Regulatory Improvement, which issued a favourable ruling on it; Whereas, in accordance with article 47, paragraph I, of the Federal Law on Metrology and Standardisation, the Draft Official Mexican Standard PROY-NOM-033-STPS-2014, Safety conditions for work in confined spaces, was published for public consultation for sixty days in the Official Gazette of the Federation of 4 November 2014, so that during that period interested parties could submit their comments to the National Advisory Committee for Standardisation on Occupational Safety and Health; Whereas, having received comments from twelve submitting parties, that Committee examined them and ruled on them in due course, and this Ministry accordingly published the respective replies in the Official Gazette of the Federation of 8 May 2015, on the basis of article 47, paragraph III, of the Federal Law on Metrology and Standardisation; Whereas, following the incorporation of the comments submitted on the Draft Official Mexican Standard PROY-NOM-033-STPS-2014, Safety conditions for work in confined spaces, and the final review of the draft itself, various amendments were made with the aim of giving clarity, consistency and legal certainty as regards the provisions that apply in workplaces, and Whereas, in view of the foregoing considerations, and given that the National Advisory Committee for Standardisation on Occupational Safety and Health granted its approval, the following is hereby issued: OFFICIAL MEXICAN STANDARD NOM-033-STPS-2015, SAFETY CONDITIONS FOR WORK IN CONFINED SPACES
CONTENTS
TRANSITORY PROVISIONS
1. Purpose
To establish the safety conditions to protect the physical integrity and life of workers who perform work in confined spaces, and to prevent impairment of their health.
2. Scope
para 2.1 This Official Mexican Standard is in force throughout the national territory and applies to all workplaces where work in confined spaces is carried out.
para 2.2 This Standard does not apply to diving activities or to underground mines, except where confined spaces exist within their facilities.
3. References
For the correct interpretation of this Standard, the following Official Mexican Standards and Mexican standards in force, or those replacing them, shall be consulted:
para 3.1 NOM-004-STPS-1999, Protection systems and safety devices on machinery and equipment used in workplaces.
para 3.2 NOM-009-STPS-2011, Safety conditions for work at height.
para 3.3 NOM-010-STPS-1999, Safety and hygiene conditions in workplaces where chemical substances capable of generating contamination in the working environment are handled, transported, processed or stored.
para 3.4 NOM-017-STPS-2008, Personal protective equipment - Selection, use and handling in workplaces.
para 3.5 NOM-018-STPS-2000, System for the identification and communication of hazards and risks from hazardous chemical substances in workplaces.
para 3.6 NOM-026-STPS-2008, Safety and hygiene colours and signs, and identification of risks from fluids conveyed in pipes.
para 3.7 NOM-027-STPS-2008, Welding and cutting activities - Safety and hygiene conditions.
para 3.8 NOM-029-STPS-2011, Maintenance of electrical installations in workplaces - Safety conditions.
para 3.9 NOM-116-STPS-2009, Safety - Personal protective equipment - Negative-pressure air-purifying respirators against harmful particles - Specifications and test methods.
para 3.10 NMX-S-002-SCFI-2004, Safety - Chemical-cartridge air-purifying respirators - Specifications and test methods.
para 3.11 NMX-S-054-SCFI-2013, Safety - Negative-pressure air-purifying respirators against harmful particles - Specifications and test methods.
4. Definitions
For the purposes of this Standard, the following definitions are taken to apply:
para 4.1 Risk analysis: The application of one or more specific methods to identify, evaluate and determine measures for the prevention and control of the significant risks associated with the conditions and activities carried out in confined spaces.
para 4.2 Hazardous atmosphere: An atmosphere that may expose a person to a risk of death, incapacitation, impairment of the ability to self-rescue, injury or serious illness from any of the following causes: flammable gases, vapours or mists above 10% of the lower flammable limit; combustible particles in the air at a concentration that may pose a risk of fire or explosion; an oxygen concentration in the air below 19.5% or above 23.5% by volume; a concentration of any hazardous chemical substance above the action level, as provided for by NOM-010-STPS-1999 or the standards that replace it; or any other atmospheric condition that constitutes an immediate danger to life or health.
para 4.3 Respirable atmosphere: An atmosphere with an oxygen concentration between 19.5% and 23.5% by volume and, where applicable, concentrations of hazardous chemical substances below the action level.
para 4.4 Labour authority: The competent administrative units of the Ministry of Labour and Social Welfare (Secretaría del Trabajo y Previsión Social) that perform inspection functions in the field of occupational safety and health, and the corresponding units of the federal states acting in support of them.
para 4.5 Workplace: The place or places, such as buildings, premises, installations and areas, where activities of exploitation, utilisation, production, marketing, transport and storage or the provision of services are carried out, and where persons subject to an employment relationship work.
para 4.6 Contaminants of the working environment: The physical, chemical and biological agents capable of modifying the environmental conditions of the workplace which, by reason of their properties, concentration, level and time of exposure or action, may impair the health of the exposed workers.
para 4.7 Contractor: The natural or legal person who works temporarily at a workplace and contractually undertakes towards the employer to carry out all or part of the work, to the extent determined by the contract, using its own or subcontracted equipment, machinery and/or labour.
para 4.8 Oxygen deficiency: An oxygen concentration below 19.5% by volume.
para 4.9 Personal protective equipment: The set of elements and devices specifically designed to protect the worker against occupational accidents and diseases.
para 4.10 Self-contained breathing apparatus: The device designed to supply breathable air, in which the source is carried by the user.
para 4.11 Confined space: A place without natural ventilation, or with deficient natural ventilation, in which one or more persons may perform a given task inside it, with limited or restricted means of access or egress, and which is not designed for continuous occupancy.
para 4.12 Immediately dangerous to life or health, IDLH (IPVS): The concentration of a toxic substance that represents an immediate threat to life, and/or that may produce irreversible adverse health effects, or that may impair a person's ability to escape from a hazardous atmosphere.
para 4.13 Lower flammable limit; lower explosive limit: The minimum concentration of any vapour or gas, as a percentage by volume of air, that ignites or explodes if a source of ignition is present at ambient temperature.
para 4.14 Emergency escape breathing device: The device that supplies the worker with a defined quantity of breathable air for escape in the event of an emergency.
para 4.15 Monitoring: Sampling carried out continuously while work is performed in the confined space.
para 4.16 Sampling: The measurement of the concentration of chemical contaminants of the working environment, of oxygen and of flammable or explosive substances in the confined space, by means of direct-reading measuring equipment.
para 4.17 Action level (AL): Half of the exposure limit value (VLE), time-weighted average, of hazardous chemical substances, in accordance with Appendix I of NOM-010-STPS-1999, or the standards that replace it.
para 4.18 Airline respirator; respiratory protective equipment with an air supply line: The device that supplies breathable air to the user at a pressure higher than atmospheric pressure, from a source that is not carried by the user.
para 4.19 Person in charge of the work: The worker designated to supervise, before and during the performance of activities in confined spaces, that the conditions for carrying out the work safely are met.
para 4.20 Risk: The correlation between the hazardousness of one or more factors and the exposure of workers, with the possibility of causing adverse effects to their life, physical integrity or health, or of damaging the workplace.
para 4.21 Serious risk: A risk that may compromise the life, physical integrity or health of workers, or cause damage to the installations of the workplace, where the corresponding safety conditions are not in place.
para 4.22 Hazardous chemical substances: Substances which, by reason of their physical and chemical properties, when handled, transported, stored or processed, present a possibility of risks of explosiveness, flammability, combustibility, reactivity, corrosiveness, radioactivity, toxicity or irritability, and which, on entering the body by the respiratory, dermal or digestive route, may cause workers poisoning, burns or organic injuries, depending on the level and concentration of the substance and the time of exposure.
para 4.23 Attendant: The worker designated to remain at all times outside the confined space while any activity is carried out inside it, to maintain contact and/or communication with the workers performing the activities, to assist them, and to alert the person in charge of the work in the event of an emergency.
5. Obligations of the employer
para 5.1 Identify the confined spaces where worker access is required to perform any type of activity.
para 5.2 Classify the confined space and have a risk analysis in place prior to worker access, carried out by personnel specifically trained for this purpose, which considers, as applicable, the risks from hazardous atmospheres and from physical or biological agents, as well as those relating to the activities to be performed, in accordance with Chapter 7 of this Standard.
para 5.3 Have safety procedures in place for: the activities to be performed; the use of equipment and tools, and the sampling and monitoring to detect hazardous atmospheres, based on the provisions of Chapter 8 of this Standard.
para 5.4 Have a specific work plan for carrying out work in confined spaces, in accordance with paragraph 8.5 of this Standard.
para 5.5 Issue written authorisations to workers for the performance of work in confined spaces, in accordance with paragraph 8.6 of this Standard.
para 5.6 Adopt the safety measures for carrying out work in confined spaces, in accordance with Chapter 9 of this Standard.
para 5.7 Designate a person in charge of the work in confined spaces and at least one attendant, who shall comply with paragraphs 9.5 and 9.6 of this Standard, respectively.
para 5.8 Provide lighting inside confined spaces, appropriate to the activities to be performed, that allows the work to be carried out safely, by means of portable lamps or equipment and/or lighting systems.
para 5.9 Provide workers with the required personal protective equipment, based on the classification of the confined space, the risk analysis and the activity to be performed, in accordance with NOM-017-STPS-2008, or the standards that replace it.
para 5.10 Have an emergency response and rescue plan that provides for the rescue of workers who may have an accident, and that includes the necessary equipment, in accordance with Chapter 10 of this Standard.
para 5.11 Provide information and training to workers who perform activities in confined spaces, according to the work to be performed, its classification and the outcome of the risk analysis, based on Chapter 11 of this Standard.
para 5.12 Verify that contractors comply with this Standard, where the employer engages the services of third parties to carry out work in confined spaces.
para 5.13 Keep records of the personnel authorised to carry out work in confined spaces; of their entry into and exit from such spaces; of their time spent inside, and of the sampling and/or monitoring of the atmosphere of those spaces.
6. Obligations of the workers
para 6.1 Observe the safety measures laid down by this Standard, as well as those established by the employer for the prevention of risks in the performance of work in confined spaces.
para 6.2 Immediately notify the employer and/or the safety and hygiene committee of any unsafe conditions they notice during the performance of their activities, as well as of any occupational accidents that occur.
para 6.3 Use and keep in good condition the personal protective equipment provided by the employer.
para 6.4 Carry out fit testing when using an airline respirator or self-contained breathing apparatus as personal protective equipment.
para 6.5 Operate the machinery, equipment and tools assigned to them in a safe manner.
para 6.6 Conduct themselves safely during the performance of the work so as to avoid risks.
para 6.7 Take part in the training, instruction and information events provided by the employer.
para 6.8 Inform the employer of any effects on their health or of any possible limitations on their ability to perform their activities in the confined space.
7. Classification of confined spaces and risk analysis
para 7.1 Work in confined spaces shall preferably be avoided; entry shall be made only to perform activities in those cases where the activity cannot be carried out from the outside and, in any event, the provisions of this Standard shall be complied with in full.
para 7.2 Before work in the confined space begins, sampling shall be carried out to determine the existence or absence of a hazardous atmosphere, in accordance with paragraph 8.4 of this Standard.
para 7.3 Based on the results of the sampling referred to in paragraph 7.2, confined spaces shall be classified as Type I or Type II, in accordance with Table 1 of this Standard. For the classification of confined spaces, reference shall be made to the exposure limit values determined by NOM-010-STPS-1999, or the standards that replace it, as well as to the information in the relevant safety data sheets, based on the provisions of NOM-018-STPS-2000, or the standards that replace it.
Table 1 Types of confined spaces In the source file the table is cut short; on this page its remaining rows are given as text: flammability characteristics - Type I below 10% of the lower flammability and/or explosibility limit, Type II at or above 10% of that limit; toxicity or danger to health (concentration) - Type I below the action level (0.5 of the VLE), Type II at or above the action level (0.5 VLE). For the purposes of this Standard, the confined space shall be classified into the following types: a) Type I confined space: one in which there is no risk from oxygen deficiency or enrichment, nor explosive or flammable atmospheres, and in which the concentrations of hazardous chemical substances are below the action level. The confined space shall be classified in this type if all three of the above criteria indicated in Table 1 are met, or b) Type II confined space: one that has the potential to cause occupational injuries and/or illnesses, and may even be immediately dangerous to life and health. A hazardous atmosphere may be present in such spaces. The confined space shall be classified in this type if at least one of the above criteria shown in Table 1 is met.
Table 1 · Types of confined spaces
| Criterion | Type I | Type II |
|---|---|---|
| Characteristic | Minimal potential risk to health | Serious or imminent risk to the health of workers |
| Oxygen concentration, per cent | Between 19.5 and 23.5% | Below 19.5%, or above 23.5% |
para 7.4 A risk analysis shall be carried out for each confined space where work is performed, and for each job to be performed in such spaces.
para 7.5 The risk analysis shall consider at least the following:
a) The description of the activities to be performed;
b) The risks from hazardous atmospheres:
1) Asphyxia, due to oxygen deficiency;
2) Fire or explosion, due to oxygen enrichment or to substances at concentrations or at a percentage greater than or equal to 10% of the lower flammable and/or explosive limit, and
3) Poisoning, due to concentrations of hazardous chemical substances, according to the information in the relevant safety data sheets, in accordance with NOM-018-STPS-2000, or the standards that replace it:
I.- From the materials introduced to carry out the activities;
II.- From the products or waste generated by the work performed;
III.- From adjacent areas or processes in which toxic substances are handled, processed or stored, and
IV.- From the hazardous chemical substances that the confined space contains or has contained;
c) The risks from physical agents:
1) Noise;
2) Lighting;
3) Vibration, and
4) High or low thermal conditions;
d) The risks from biological agents, such as the presence of harmful fauna or dangerous biological agents;
e) Mechanical, electrical or pneumatic risks;
f) The risks arising from the activities to be performed, considering, as applicable, the following:
1) The machinery, equipment, tools and materials at the place of work, with emphasis on the characteristics and the safety and operating conditions in which they are required to be;
2) The hazards and risk factors existing due to the activities to be performed and those originating in the vicinity of the confined space from other activities, such as connection of power, operation of machinery or equipment, restoration of the flow of substances, flooding, among others, and
3) The performance of work at height;
g) The risks arising from the characteristics of the confined space, among others:
1) From the condition of the surfaces of the confined space: unstable, wet, slippery, among others, and
2) From the existence of finely divided granular material, or material in such a form that it may cause a risk of sinking into or being engulfed by that material;
h) The estimated duration of the activities to be performed;
i) The maximum time the worker may remain in the confined space, and
j) The possible emergency situations that may arise during the performance of the work in the confined space.
para 7.6 The risk analysis shall consider the cases in which a confined space initially classified as Type I may become a Type II confined space as a consequence of the activities performed in it.
para 7.7 Based on the outcome of the risk analysis, the prevention and control measures applicable to the risks identified shall be determined, and they shall include the safety measures laid down in Chapter 9 of this Standard.
para 7.8 The risk analysis shall be:
a) Available for consultation by the workers who take part in or perform activities in confined spaces, and
b) Approved and signed by the employer, or the employer's representative, and by the person responsible for the preventive occupational safety and health services.
para 7.9 The risk analysis shall be reviewed, updated or modified when:
a) New tools, equipment or substances are introduced;
b) The conditions inside the confined space change;
c) An incident or accident has occurred, or
d) A risk not provided for in the safety procedures is detected.
8. Administrative requirements for work in confined spaces
para 8.1 To perform activities in confined spaces, safety procedures shall be in place, available to the workers involved in those activities, and kept up to date, for:
a) The activities to be performed;
b) The use of equipment and tools, and
c) The sampling and monitoring to detect hazardous atmospheres.
para 8.2 The safety procedure for the activities to be performed in confined spaces shall consider the following:
a) The means of communication between the personnel performing the activities in the confined space and the attendant;
b) The way a respirable atmosphere is to be maintained or, failing that, the obligation to use respiratory protective equipment with an air supply line or self-contained breathing apparatus. Where an airline respirator is used, an emergency escape breathing device shall be available for escape in the event of an emergency;
c) The information, where applicable, from the safety data sheets of the hazardous chemical substances handled, in accordance with NOM-018-STPS-2000, or the standards that replace it;
d) The specific safety measures to be adopted, in addition to those laid down in Chapter 9 of this Standard;
e) The criteria for avoiding or interrupting the activities where the safety or health of the workers is compromised;
f) The estimated duration of the activities to be performed and the maximum time workers may remain inside;
g) The application, before the start of the activities, of means of blocking the flow of substances, such as those conveyed in pipes, and/or of energy, through the use of tags and padlocks, as well as of equipment or devices, based on the provisions of NOM-004-STPS-1999 and NOM-029-STPS-2011, or the standards that replace them, and
h) The emergency response and rescue plan for workers who may have an accident.
para 8.3 The safety procedures for the use of equipment and tools in the activities performed in confined spaces shall take into account the manufacturer's instructions and shall include the following:
a) The instructions for verifying their correct operation;
b) The use, handling, limitations, inspection and maintenance of the personal protective equipment and the information on the capacity or degree of protection it offers, as well as the conditions in which it does not provide protection or where it is not to be used;
c) The actions to be taken before, during and after the use of the personal protective equipment, to verify that it continues to provide the protection for which it was designed;
d) The verification that, where the worker is exposed to contaminants of the working environment, the personal protective equipment used is designed to protect the worker against that agent;
e) The safe way to use the equipment and tools;
f) The manner in which the decontamination or disinfection of the personal protective equipment is to be carried out, as applicable, after each shift of use, in accordance with the manufacturer's instructions;
g) The mechanism to be followed to immediately replace or repair the personal protective equipment where inspection shows any deterioration that prevents its proper functioning, and
h) The correct way to store the personal protective equipment and, where applicable, its final disposal.
para 8.4 The sampling and monitoring to detect hazardous atmospheres in the confined space shall be carried out in accordance with a procedure that includes the following:
a) The measuring equipment required to carry out the sampling and monitoring, which shall meet the following characteristics:
1) Be direct-reading;
2) Have a danger alarm for the detection of a hazardous atmosphere;
3) Be protected against electromagnetic emissions or radio-frequency interference, and
4) Be explosion-proof or intrinsically safe;
b) The calibration of the direct-reading measuring equipment in accordance with the manufacturer's instructions or manuals;
c) The functional tests to be performed on the direct-reading measuring equipment before use, to verify its correct performance, based on the manufacturer's instructions;
d) The way the initial sample is to be taken, from outside the confined space;
e) The taking of samples in several zones of the confined space, including at least the upper part, the middle and the bottom of the confined space, to determine the following:
1) The percentage of oxygen;
2) The percentage of the lower flammable and/or explosive limit, and
3) The concentrations of toxic contaminants of the working environment, and
f) The timing and frequency of sampling while the work is performed, as determined by the employer in accordance with the risk analysis, for Type I spaces, and continuous sampling and monitoring for spaces classified as Type II.
para 8.5 The work plan for carrying out the activities in the confined space shall contain the following:
a) The description of the activity to be performed;
b) The name of the person in charge of the work and of the attendant;
c) The names of the workers taking part in the activity, who shall have the training required to perform the work, in accordance with Chapter 11 of this Standard;
d) The estimated time for performing the activity, indicating the start and finish times;
e) The place where the activity will be performed;
f) The authorisation required to carry out the work, based on paragraph 8.6 of this Standard;
g) The risks determined in accordance with paragraph 7.5 of this Standard;
h) The personal protective equipment and the equipment, machinery and work tools required to perform the activity;
i) The safety measures required, according to the risks that may arise while performing the work, and
j) The safety procedures for performing the activities.
para 8.6 The authorisation for carrying out work in confined spaces shall contain the following:
a) The identification, location and classification of the confined space;
b) The expiry date and time of the authorisation, which shall be valid for no longer than one work shift. The authorisation shall be updated for each additional shift required;
c) The risks identified, in accordance with the risk analysis referred to in Chapter 7 of this Standard;
d) The verification that the isolation of the confined space has been carried out, considering, as applicable:
1) The sealing and/or disconnection of sources of energy, fluids, among others;
2) The blocking of electrical equipment or devices, based on the provisions of NOM-029-STPS-2011, or the standards that replace it, and
3) The mechanical blocking of equipment and tools, in accordance with NOM-004-STPS-1999, or the standards that replace it;
e) The initial readings of the concentrations in the confined space, taken before the start of the activities, indicating:
1) The percentage of oxygen;
2) The percentage of the lower flammable and/or explosive limit, and
3) The concentrations of toxic substances;
f) The frequency of sampling while the work is performed, as determined by the employer for Type I spaces, and continuous sampling and monitoring for spaces classified as Type II;
g) The verification that the worker has the training required to perform the work, and on the identification and control of hazards and risks;
h) The emergency procedures and the location of the first-aid and/or rescue equipment;
i) The personal protective equipment required, according to the risk to which the workers are exposed;
j) The explosion-proof installations, tools and/or electrical equipment required, where applicable;
k) The maximum time the worker may remain in the confined space, determined on the basis of the risk analysis;
l) The entry and exit times of the worker(s);
m) The approval of the physician or of the person in charge of the work regarding the physical fitness of the worker who will enter the confined space;
n) The name and signature of the attendant;
o) The name and signature of the person in charge of the work, and
p) The name and signature of the person who authorises the work.
9. Safety measures for work in confined spaces
para 9.1 The following general safety measures shall be adopted for carrying out work in confined spaces:
a) Signpost the entrance to all accesses to the confined spaces in which work is being carried out, in accordance with NOM-026-STPS-2008, or the standards that replace it;
b) Demarcate and control access to the confined space, and display visibly, at the entrance to that space, the authorisation issued for the performance of the corresponding work;
c) Carry out work in confined spaces only with workers trained and authorised to do so;
d) Have means of communication between the personnel performing the activities in the confined space and the attendant;
e) Have, where applicable, specific instructions for carrying out hot work, including the necessary safety measures and the conditions under which it may not be carried out;
f) Provide workers with a personal fall arrest system where a risk of falling from height exists, in accordance with NOM-009-STPS-2011, or the standards that replace it;
g) Provide workers with at least a harness and a rescue line so that they can be extracted in the event of an emergency, in such a way that these elements do not constitute a risk factor, and if the risk analysis so determines, and
h) Carry out welding or cutting activities in accordance with NOM-027-STPS-2008, or the standards that replace it;
i) Comply with NOM-029-STPS-2011, or the standards that replace it, where maintenance activities on electrical installations are carried out inside the confined space;
j) Provide workers with portable equipment to detect oxygen deficiency, flammable or explosive atmospheres, and the concentration of chemical contaminants of the working environment, on the following basis:
1) For Type I confined spaces, to at least one of the workers. Where several work groups work simultaneously under different environmental conditions, at least one worker of each group shall be provided with such portable equipment, and
2) For Type II confined spaces, it shall be provided to all workers;
k) Use explosion-proof installations, tools, luminaires and electrical equipment in confined spaces where flammable or explosive substances or their residues may potentially be present;
l) Use, where applicable, personal luminaires with low safety voltages of up to 24 volts;
m) Verify, where applicable, that earthing systems or elements for draining static electricity from the equipment and the workers are in place, in confined spaces where a risk of fire or explosion exists;
n) Carry out the initial sampling of the concentrations in the atmosphere of the confined space, in accordance with the procedure referred to in paragraph 8.4 of this Standard;
o) Compare the concentrations existing in the confined space with the exposure limit values indicated by NOM-010-STPS-1999, or the standards that replace it, provided that the measurement can be taken with the direct-reading equipment, to verify that they are below the action level and allow the activities to be carried out safely;
p) Use respiratory protective equipment with an air supply line or self-contained breathing apparatus, as well as the additional personal protective equipment with the highest level of protection, in accordance with the risk analysis provided for in paragraph 7.4 of this Standard, where the comparison indicated in subparagraph o) of this paragraph cannot be complied with;
q) Maintain a respirable atmosphere by means of natural or forced ventilation systems and, where this is not possible, use respiratory protective equipment with an air supply line or self-contained breathing apparatus, in accordance with paragraphs 9.2, 9.3 and 9.4;
r) Establish the criteria for interrupting the work where any condition arises that may generate a risk;
s) Cancel the authorisation for carrying out the work once it is completed or suspended; in the latter case the activities may resume when the person in charge of the work verifies that the conditions indicated in the authorisation are maintained, based on paragraph 8.6 of this Standard;
t) Interrupt and prohibit the work when the percentage of flammability and/or explosiveness in the confined space is greater than or equal to 10% of the lower limit;
u) Prohibit access to the confined space by workers who are not fit to perform this type of activity (who do not have the approval of the physician or of the person in charge of the work regarding their physical fitness);
v) Prohibit the performance of the work where the safety procedures are not in place; the safety measures are not applied; the necessary personal protective equipment is not available; the materials, tools or equipment necessary to perform the activity are not available, or any other anomaly arises that compromises the safety of the workers;
w) Prohibit workers from exceeding the maximum time of stay indicated in the corresponding authorisation;
x) Prohibit any work in confined spaces from being carried out alone, and from lasting longer than one work shift or eight hours;
y) Prohibit minors under 18 years of age and pregnant women from performing activities in confined spaces, and
z) Prohibit the introduction of machinery or internal-combustion equipment into confined spaces.
para 9.2 To perform activities safely in confined spaces classified as Type II, the appropriate technical and/or administrative control measures shall be adopted.
para 9.3 The technical control measures referred to in paragraph 9.2 of this Standard shall comprise, as applicable, the following:
a) Determine the method to be used for the ventilation and/or purging of the confined space, according to the risk analysis, the work to be performed and the characteristics of the space, avoiding the contamination of other areas of the workplace;
b) Control the atmosphere of the confined space by means of ventilation and/or purging;
c) Implement, where applicable, a cleaning process for the confined space;
d) Locate the controls of the fans at a safe distance from the confined space;
e) Establish the cases in which continuous ventilation is used, and install, where applicable, an audible warning device to alert of the occurrence of a ventilation failure;
f) Verify, where applicable, that the ventilation system does not block access to the confined space or limit communication between the personnel performing the activities in the confined space and the attendant;
g) Prevent the recirculation of contaminated air into the confined space;
h) Prohibit ventilation by means of pure oxygen, and state this in the safety procedure determined in paragraph 8.2 of this Standard;
i) Measure the concentrations of the atmosphere of the confined space in accordance with the procedure for taking measurements to detect hazardous atmospheres set out in paragraph 8.4, after carrying out the ventilation or purging, and
j) Verify that the concentration levels are below the action level, the oxygen concentration is within the range of 19.5% to 23.5%, and the percentage of flammability is below 10% of the lower flammable and/or explosive limit.
para 9.4 In Type II confined spaces where it is not possible to maintain respirable atmospheres, the following administrative control measures shall be adopted:
a) Review the duration of the activities and, where applicable, reschedule the activities and/or redefine the duration of the work, and
b) Have and follow up a respiratory protection programme containing the following elements:
1) The record of the measurements of the concentrations inside the confined space;
2) The supply of high-efficiency respiratory protective equipment and, where a high concentration or a concentration immediately dangerous to life and/or health exists, self-contained breathing apparatus or an airline respirator;
3) The medical evaluations of the personnel required to use respirators for entry into the confined space, to determine:
I.- The worker's fitness to use negative-pressure and positive-pressure respirators, as applicable;
II.- The worker's ability to see and hear warnings, according to the communication and/or alarm system in place, such as flashing lights, bells or sirens, among others;
III.- The worker's fitness to carry out the assigned tasks, and
IV.- The existence of any illness or anomaly that could make it difficult to use the respiratory protective equipment or to perform the activities inside the confined space;
4) The criteria for the selection of filters and cartridges, based on the provisions of NOM-116-STPS-2009 and/or Mexican standards NMX-S-002-SCFI-2004 and NMX-S-054-SCFI-2013, on respirators, or the standards that replace them;
5) The procedure for checking the fit and testing the tightness of the respirators;
6) The instructions for the normal use of the respirators and for their use in emergency situations;
7) The instructions for checking the quality, quantity and flow of the air to be supplied to the worker, where self-contained breathing apparatus or airline respirators are used;
8) The instructions for the maintenance, cleaning, disinfection, care, storage, inspection, repair, replacement and final disposal of the respirators, and
9) The training and information for the personnel required to use respiratory protective equipment, including the limitations on its use.
para 9.5 The person in charge of the work in the confined space shall comply with the following:
a) Have the training required to perform the functions determined by this paragraph;
b) Ensure that the attendant, positioned outside the space, remains there at all times while there is personnel in the confined space;
c) Verify, before the start of the activities, as applicable, that means of blocking energy, fluids, pressure, among others, are put in place through the use of tags and padlocks, as well as of equipment or devices, in accordance with NOM-004-STPS-1999 and NOM-029-STPS-2011, or the standards that replace them;
d) Prepare and/or process the authorisation for carrying out the work in confined spaces, and cancel it once the work is completed or suspended;
e) Verify, as applicable, that the workers have the work plan and the authorisation referred to in paragraphs 8.5 and 8.6 of this Standard, respectively, and that the authorisation is displayed at the entrance to the confined space;
f) Supervise that the work is carried out safely, in accordance with the provisions of this Standard;
g) Ensure that the environmental conditions of the confined spaces are evaluated during the performance of the work, to verify that they allow the activities to be carried out safely;
h) Verify that the safety procedures referred to in Chapter 8 of this Standard are in place;
i) Verify that the tests or checks of the measuring equipment are carried out before its use;
j) Check that the resources for emergency response are available before the start of the work in the confined space, and
k) Supervise the carrying-out of the emergency response and rescue plan.
para 9.6 The attendant for the work in the confined space shall comply with the following:
a) Have the training required to perform the functions determined by this paragraph;
b) Remain at all times during the performance of the work outside the confined space, next to the entrance, in communication with the personnel performing the activities in the confined space;
c) Interrupt the work or order the evacuation of the confined space where any condition arises that may generate a serious or imminent risk, or any other condition that puts the workers at risk or complicates their exit;
d) Keep control of the number of workers entering the confined space and verify that all of them leave once the activities are completed;
e) Ensure that the times of stay in the confined space are not exceeded, and
f) Alert the person in charge of the work of the occurrence of an emergency.
10. Emergency response and rescue plan
para 10.1 The emergency response and rescue plan shall consider the emergency situations that may arise during work in the confined space, identified in the risk analysis.
para 10.2 The emergency response and rescue plan shall contain at least the following:
a) The scope of the plan according to the work performed, the type of confined space and the risk analysis;
b) The conditions under which the emergency and rescue personnel, both internal and external, may or may not enter the confined space;
c) The person responsible for implementing the plan;
d) The human and material resources for its execution, indicating the names of the workers designated and trained to apply the plan, as well as the function assigned to each of them;
e) The training required of the workers in relation to the content of the plan, considering the type of confined space;
f) The personal protective and rescue equipment required for emergency response;
g) The inventory of the material resources required and available to deal with emergency situations, and
h) The procedures for:
1) Raising the alarm, in the event of an emergency;
2) Internal and external communication in the event of an emergency, together with the directory of the emergency assistance services (fire service, hospitals and rescue), as well as, where applicable, the directory of the information centres for the handling of chemical substances in emergencies;
3) Shutting down the machinery and equipment;
4) Suspending the activities;
5) Rescuing workers who have had an accident;
6) Evacuating the workers who are at risk, according to the emergency situation(s) that may arise, including workers and persons with disabilities who do not work in the confined space and who are presumed to be at risk;
7) First aid, and
8) Eliminating the risks after the emergency, where applicable.
11. Training
para 11.1 The information provided to workers shall include the outcome of the risk analysis of each of the confined spaces.
para 11.2 Workers involved in the performance of activities in confined spaces shall be provided with training, with emphasis on risk prevention, based on the type of confined space and the tasks assigned, as well as on the emergency response and rescue plan.
para 11.3 The training and instruction provided to workers shall consist of theoretical instruction, practical training and an evaluation of the knowledge and skills acquired, and shall consider the following:
a) The content of this Standard, with emphasis on the application of the safety measures;
b) The hazards and risks present in the confined space;
c) The risks arising from the properties of the chemical substances present in the confined space;
d) The effects that exposure to the chemical substances may cause and the corresponding physical and health hazards;
e) The way to work safely, the safety procedures and the authorisations required to perform the activity;
f) The correct way to operate, inspect and store, where applicable, the ventilation equipment installed or used for work in confined spaces;
g) The respiratory protection programme, where applicable;
h) The use of the respiratory protective equipment, including the limitations on its use;
i) The correct use of the personal protective equipment, in accordance with NOM-017-STPS-2008, or the standards that replace it;
j) The use, handling and reading of personal measuring equipment, and
k) The application of the emergency response and rescue plan, including the performance of drills on the possible emergency situations that may arise, provided for in the risk analysis.
para 11.4 In addition to the provisions of paragraphs 11.2 and 11.3, the person in charge and the attendant of the work in confined spaces shall be trained, instructed and evaluated in the following subjects:
a) The procedure for sampling the concentrations of the atmosphere of the confined space;
b) The evaluation of the concentrations obtained;
c) The cases in which the activities shall be suspended, and
d) The specific actions they shall take for emergency response and rescue.
para 11.5 Workers who are members of the rescue team shall be trained specifically in the emergency response and rescue plan, with emphasis on the use of personal protective and rescue equipment, as well as in the application of the procedures referred to in that plan.
para 11.6 The training and instruction shall be reinforced at least once a year, or earlier where any of the following circumstances arises:
a) New tools or equipment are introduced, or the conditions inside the confined space change;
b) An incident or accident has occurred;
c) Unsafe operation of the equipment becomes evident, or
d) The most recent evaluation applied to the workers performing activities in confined spaces so suggests.
para 11.7 Workplaces shall keep a record of the training and instruction provided to workers, which shall contain at least the following:
a) The name and position of the workers to whom it was provided;
b) The date on which the training was provided;
c) The subjects taught, and
d) The name of the instructor and, in the case of training providers external to the workplace, the registration number with the Ministry of Labour and Social Welfare.
12. Verification units
para 12.1 The employer shall have the option of engaging an accredited and approved verification unit, under the terms of the Federal Law on Metrology and Standardisation and its Regulations, to verify the degree of compliance with this Standard.
para 12.2 The verification units that assess conformity with this Standard shall apply the compliance criteria provided for in the conformity assessment procedure, in accordance with Chapter 13 of this Standard.
para 12.3 The accredited and approved verification units that assess compliance with this Standard shall issue a verification opinion, which shall contain:
a) Details of the workplace verified:
1) The name, denomination or company name;
2) The Federal Taxpayers Registry;
3) The complete address;
4) The telephone number, and
5) Its main activity;
b) Details of the verification unit:
1) The name, denomination or company name;
2) The accreditation number;
3) The approval number granted by the Ministry of Labour and Social Welfare, and
4) Its complete address, and
c) Details of the opinion:
1) The code and name of the standard;
2) The name of the evaluated and approved verifier;
3) The date of verification;
4) The number of the opinion;
5) The validity of the opinion;
6) The place of issue of the opinion;
7) The date of issue of the opinion, and
8) The registration number of the opinion issued by the Ministry of Labour and Social Welfare, when the corresponding report is submitted.
para 12.4 The validity of the opinions issued by the verification units shall be one year, provided that the conditions on which their issue was based are not modified.
13. Conformity assessment procedure
para 13.1 This conformity assessment procedure applies both to the inspection visits carried out by the labour authority and to the verification visits carried out by the verification units.
para 13.2 The current verification opinion shall be made available to the labour authority upon request.
para 13.3 The aspects to be verified during the assessment of conformity with this Standard shall be checked, as applicable, by means of physical verification, documentary review, records or interviews, in accordance with the following: Type of Provision Acceptance criterion Observations Risk check
para 5.1 (PEC) Documentary. The employer complies when it presents documentary evidence that it identifies the confined spaces where access by the worker is required to carry out any type of activity. This requirement is met by means of a list indicating the confined spaces of the workplace where access by the worker is required.
requires the worker's access to the confined perform any type of activity. spaces of the workplace
para 5.2 (PEC) and 7 Documentary. The employer complies when it presents documentary evidence that: Serious
- It classifies the confined space and has a risk analysis prior to the entry of workers, covering, as applicable, the risks from hazardous atmospheres, from physical or biological agents, and those relating to the activities to be performed,
- It carries out sampling to determine the existence or non-existence of a hazardous atmosphere, before work begins in the confined space, in accordance with paragraph 8.4 of this Standard; Serious
- It takes as a reference for classifying confined spaces the exposure limit values determined by NOM-010-STPS-1999, or the standards that replace it, and the information in the respective safety data sheets, on the basis of NOM-018-STPS-2000, or the standards that replace it;
- It classifies confined spaces as Type I or Type II from the results of the sampling referred to in paragraph 7.2, in accordance with Table 1 of this Standard, as follows: Serious
- As Type I, the confined space in which there is no risk of oxygen deficiency or enrichment, nor explosive or flammable atmospheres, and in which the concentrations of hazardous chemical substances are below the action level. The confined space shall be classified in this type if the three criteria of Table 1 of this Standard are met, and
- As Type II, the confined space that has the potential to cause occupational injuries and/or illnesses, and may even be immediately dangerous to life and health. The confined space shall be classified in this type if at least one of the criteria of Table 1 of this Standard is met;
- It carries out a risk analysis for each confined space where work is performed, and for each job to be carried out in those confined spaces; Serious
- The risk analysis is drawn up by personnel trained in risk analysis in confined spaces;
- The risk analysis considers at least the following: Serious
- The description of the activities to be performed;
- The risks from hazardous atmospheres: o Asphyxiation, owing to oxygen deficiency; o Fire or explosion, from oxygen enrichment or from substances with concentrations at or above 10% of the lower flammability and/or explosivity limit, and o Poisoning, on account of concentrations of hazardous chemical substances, in accordance with the information in the respective safety data sheets and with NOM-018-STPS-2000, or the standards that replace it;
- From the materials brought in to carry out the activities;
- From the products or waste generated by the work carried out;
- From adjacent areas or processes in which toxic substances are handled, processed or stored, and
- From the hazardous chemical substances that the confined space contains or has contained;
- The risks from physical agents: o Noise; o Lighting; o Vibration, and o Raised or lowered thermal conditions;
- The risks from biological agents, such as the presence of harmful fauna or dangerous biological agents;
- The mechanical, electrical or pneumatic risks;
- The risks arising from the activities to be performed, covering, as applicable, the following: o The machinery, equipment, tools and materials at the workplace, with emphasis on the characteristics and the safety and operating conditions in which they are to be found; o The hazards and risk factors existing on account of the activities to be performed and those arising in the vicinity of the confined space from other activities, such as the connection of energy, the operation of machinery or equipment, the restoration of the flow of substances, flooding, among others, and o The performance of work at height;
- The risks arising from the characteristics of the confined space, among others: o From the conditions in which the surfaces of the confined space are found: unstable, damp, slippery, among others, and o From the presence of finely divided granular material, or material in such a form that it may give rise to the risk of sinking or immersion in that material;
- The estimated duration of the activities to be performed;
- The maximum time the worker may remain in the confined space, and
- The possible emergency situations that may arise while the work in the confined space is being carried out;
- The risk analysis considers the cases in which a confined space initially classified as Type I may become a Type II confined space as a consequence of the activities carried out in it; Serious
- The risk analysis is: - Available to the workers who take part in or perform activities in confined spaces, and - Approved and signed by the employer, or the employer's representative, and by the person responsible for the preventive occupational safety and health services;
- The risk analysis is reviewed, updated or amended when: - New tools, equipment or substances are introduced; - The conditions inside the confined space are altered; - An incident or accident has occurred, or - A risk not foreseen in the safety procedures is detected, and
- From the result of the risk analysis it determines the prevention and control measures applicable to the risks detected, which cover the safety measures laid down in Chapter 9 of this Standard.
Carries out sampling to Serious determine the existence or
may present a hazardous atmosphere. The space shall be classified
emergencies that may arise during the
para 5.2 (PEC, continued) and 7.6 a) Physical check. The employer complies when, during a walkthrough of the workplace, it is verified that the risk analysis is available for consultation by the workers who take part in or perform activities in confined spaces.
Interview. The employer complies when, on interviewing the workers selected according to the sampling criterion of Table 2 of paragraph 13.4, it is verified that the risk analysis is available for consultation by the workers who take part in or perform activities in confined spaces. (Provisions checked: 5.3, 8.1, 8.2 - Documentary; the employer complies when it presents.)
para 8.3 (PEC) and 8.4 documentary evidence that:
- It has up-to-date safety procedures for: - The activities to be performed; - The use of equipment and tools, and - Sampling and monitoring to detect hazardous atmospheres;
- The safety procedure for the activities to be performed in confined spaces takes into account the following:
- The means of communication between the personnel performing the activities in the confined space and the attendant;
- How to maintain a respirable atmosphere or, failing that, the obligation to use respiratory protective equipment with an air supply line or self-contained breathing apparatus. Where a respirator with an air supply line is used, an alternative means of breathing is provided for escape in an emergency;
- The information, where applicable, in the safety data sheets of the hazardous chemical substances handled, in accordance with NOM-018-STPS-2000, or the standards that replace it;
- The specific safety measures to be adopted, in addition to those determined by Chapter 9 of this Standard;
- The criteria for avoiding or stopping the activities where the safety or health of the workers is compromised;
- The estimated duration of the activities to be performed and the maximum time of stay;
- The application, before the activities begin, of means of isolating the flow of substances, such as those conveyed in pipework, and/or of energy, through the use of tags and padlocks, and of equipment or devices, on the basis of NOM-004-STPS-1999 and NOM-029-STPS-2011, or the standards that replace them, and
- The emergency response and rescue plan for workers who may be injured;
- The safety procedures for the use of equipment and tools in the activities performed in confined spaces take into account:
- The manufacturer's instructions;
- The instructions for verifying their correct functioning;
- The use, handling, limitations, checking and maintenance of the personal protective equipment and the information on the capacity or degree of protection it offers, and the conditions under which it does not provide protection or is not to be used;
- The actions to be carried out before, during and after the use of the personal protective equipment, to confirm that it continues to provide the protection for which it was designed;
- Verification that, where the worker is exposed to contaminants of the working environment, the personal protective equipment used is designed to protect the worker against that agent;
- The safe way to use the equipment and tools;
- The way to decontaminate or disinfect the personal protective equipment, as applicable, after each shift of use, in accordance with the manufacturer's instructions;
- The mechanism to be followed to replace or repair the personal protective equipment immediately where, following its inspection, it shows deterioration that prevents its optimum functioning, and
- The correct way to store the personal protective equipment and, where applicable, its final disposal, and
- The procedure for sampling and monitoring to detect hazardous atmospheres in the confined space includes the following:
- The measuring equipment required to carry out the sampling and monitoring, which - This provision is met where the employer has equipment meeting the characteristics set out in this paragraph - gives warning of the detection of a hazardous atmosphere; o Being protected against electromagnetic emissions or radio-frequency interference, and o Being explosion-proof or intrinsically safe;
- The calibration of the direct-reading measuring equipment in accordance with the manufacturer's instructions or manuals;
- The functional tests carried out on the direct-reading measuring equipment before its use, so as to confirm its correct performance, on the basis of the manufacturer's instructions;
- How the initial sample is to be taken, from outside the confined space;
- The taking of samples in several zones of the confined space, including at least the upper, middle and bottom parts of the confined space, so as to determine: o The percentage of oxygen; o The percentage of the lower flammability and/or explosivity limit, and o The concentrations of toxic contaminants of the working environment, and
- The time and frequency of sampling while the work is carried out, as the employer determined in accordance with the risk analysis, for Type I spaces, and continuous sampling and monitoring in the case of spaces classified as Type II.
The mechanisms of communication between the
alternate breathing for escape in case of
safety measures to adopt, additional to those that
The instructions for verifying its correct
meets the following the manufacturer's
characteristics: guarantee or a
certificate issued
- Be direct-reading;
by it, which
- Have an alarm for indicate that theof a hazardous the characteristics atmosphere; indicated in this
- Be proof against
explosion orpara 5.3 (PEC) and 8.1 Physical check. The employer complies when, during a walkthrough of the workplace, it is verified that the safety procedures for the activities to be performed; the use of equipment and tools, and the sampling and monitoring to detect hazardous atmospheres are available to the workers involved in the activities in confined spaces.
Interview. The employer complies when, on interviewing the workers selected according to the sampling criterion of Table 2 of paragraph 13.4, it is verified that the safety procedures for the activities to be performed; the use of equipment and tools, and the sampling and monitoring to detect hazardous atmospheres are available to the workers involved in the activities in confined spaces.
para 5.4 (PEC) and 8.5 Documentary. The employer complies when it presents documentary evidence that:
- It has a specific work plan for carrying out work in confined spaces, and
- The work plan for carrying out the activities in the confined space contains the following:
- The description of the activity to be performed;
- The name of the person in charge of the work and of the attendant;
- The names of the workers taking part in the activity, who have the training required to carry out the work, in accordance with Chapter 11 of this Standard;
- The estimated time for carrying out the activity, stating the start and finish times;
- The place where the activity is performed;
- The authorisation required to carry out the work, on the basis of paragraph 8.6 of this Standard;
- The risks determined in accordance with paragraph 7.5 of this Standard;
- The personal protective equipment and the equipment, machinery and work tools required to carry out the activity;
- The safety measures required, according to the risks that may arise while the work is being performed, and
- The safety procedures for carrying out the activities.
para 5.5 (PEC) and 8.6 Documentary. The employer complies when it presents - Serious - documentary evidence that:
- It issues written authorisations to workers for the performance of work in confined spaces, and
- The authorisation for carrying out work in confined spaces contains the following:
- The identification, location and classification of the confined space;
- The date and time of expiry of the authorisation, which is valid only for up to one work shift; the authorisation is renewed for each additional shift required;
- The risks identified, in accordance with the risk analysis referred to in Chapter 7 of this Standard;
- Verification that the isolation of the confined space was carried out, considering, as applicable: fluids, among others; o The isolation of electrical equipment or devices, on the basis of NOM-029-STPS-2011, or the standards that replace it, and o The mechanical isolation of equipment and tools, in accordance with NOM-004-STPS-1999, or the standards that replace it;
- The initial readings of the concentrations in the confined space, taken before the activities begin, indicating: o The percentage of oxygen; o The percentage of the lower flammability and/or explosivity limit, and o The concentrations of toxic substances;
- The frequency of sampling while the work is carried out, as determined by the employer, for Type I spaces, and continuous sampling and monitoring in the case of spaces classified as Type II;
- Verification that the worker has the training required to carry out the work and on the identification and control of hazards and risks;
- The emergency procedures and the location of the first-aid and/or rescue equipment;
- The personal protective equipment required, in accordance with the risk to which the workers are exposed;
- explosion, where required;
- The maximum time the worker may remain in the confined space, determined on the basis of the risk analysis;
- The time of entry and exit of the worker(s);
- The approval of the physician or of the person in charge of the work as to the physical fitness of the worker who will enter the confined space;
- The name and signature of the attendant;
- The name and signature of the person in charge of the work, and
- The name and signature of the person who authorises the work.
5.6, 9.1, 9.2 and Physical. The employer complies when, on carrying out a Serious
- The sealing and/or
disconnection of the
energy sources,The installations, tools and/or electrical equipment proof against
para 9.3 (PEC) walkthrough of the workplace, it is verified that:
- It adopts the following general safety measures for carrying out work in confined spaces:
- It signposts the entrance to all accesses to the confined spaces in which work is being carried out, in accordance with NOM-026-STPS-2008, or the standards that replace it;
- It demarcates and controls access to the confined space;
- It displays visibly, at the entrance to that space, the authorisation issued for the performance of the corresponding work;
- It has means of communication between the personnel performing the activities in the confined space and the attendant;
- It provides workers with a personal fall-arrest system where there is a risk of falling from height, in accordance with NOM-009-STPS-2011, or the standards that replace it;
- It provides workers with, as a minimum, a harness and a rescue line so that they can be extracted in an emergency, in such a way that these items do not themselves constitute a risk factor, and where the risk analysis so determines;
- It carries out welding or cutting activities in accordance with NOM-027-STPS-2008, or the standards that replace it;
- It complies with NOM-029-STPS-2011, or the standards that replace it, where maintenance activities on electrical installations are carried out inside the confined space;
- It equips workers with portable measuring devices for oxygen, flammable or explosive substances and the concentration of chemical contaminants of the working environment, on the following basis: o For Type I confined spaces, at least one of the workers. Where several work groups operate simultaneously under different environmental conditions, it equips at least one worker of each group with such portable devices, and o For Type II confined spaces, all workers are provided with them;
- It uses, where applicable, personal-type luminaires with safety extra-low voltage, up to 24 volts - tools, luminaires and electrical equipment are explosion-proof;
- It confirms, where applicable, that earthing systems or elements are provided to drain static electricity from the equipment and from the workers, in confined spaces where there is a risk of fire or explosion;
- It uses respiratory protective equipment with an air supply line or self-contained breathing apparatus, and the additional personal protective equipment with the highest level of protection, in accordance with the risk analysis provided for in paragraph 7.4 of this Standard, where the comparison indicated in subparagraph o) of this paragraph cannot be complied with;
- It maintains a respirable atmosphere by means of natural or forced ventilation systems and, where this is not possible, uses respiratory protective equipment with an air supply line or self-contained breathing apparatus, in accordance with paragraphs 9.2, 9.3 and 9.4;
- It cancels the authorisation to carry out the work once the work is finished or suspended; in the latter case the activities are resumed only when the person in charge of the work verifies that the conditions indicated in the authorisation are maintained, on the basis of paragraph 8.6 of this Standard;
- It stops and prohibits the work where in the confined space the flammability and/or explosivity percentage is at or above 10% of the lower limit;
- It prohibits access to the confined space by workers who are not fit to carry out this type of activity (who do not have the approval of the physician or of the person in charge of the work as to their physical fitness);
- It prohibits work from being carried out where the safety procedures are not available; where the safety measures are not applied, where the necessary personal protective equipment is not available, where the materials, tools or equipment needed to carry out the activity are not available, or where any other abnormality arises that compromises the safety of the workers;
- It prohibits workers from exceeding the maximum time of stay indicated in the corresponding authorisation;
- It prohibits any work in confined spaces from being carried out alone, or from lasting longer than one work shift or eight hours;
- It prohibits persons under 18 years of age and pregnant women from performing activities in confined spaces, and
- It prohibits internal-combustion machinery or equipment from being brought inside confined spaces;
- To carry out the activities safely in confined spaces classified as Type II, it adopts the technical and/or administrative control measures that apply, and
- The technical control measures referred to in paragraph 9.2 of this Standard comprise, as applicable, the following:
- It controls the atmosphere of the confined space by means of ventilation and/or purging;
- It puts in place, where applicable, a cleaning process for the confined space;
- It locates the fan controls at a safe distance from the confined space;
- It installs, where applicable, an audible warning device to give notice of a failure in the ventilation;
- It verifies, where applicable, that the ventilation system does not block access to the confined space or limit communication between the personnel performing the activities in the confined space and the attendant;
- It prevents the recirculation of contaminated air into the confined space;
- It prohibits ventilation by means of pure oxygen, and
- It measures the concentrations of the atmosphere of the confined space in accordance with the procedure for taking measurements to detect hazardous atmospheres set out in paragraph 8.4, after ventilation or purging has been carried out.
carry out activities of maintenance on the
portable equipment to detect deficiency of oxygen, atmospheres
Uses installations, This provision is tools, luminaires and met when the explosion-proof electrical employer has the equipment, in the confined manufacturer's spaces where guarantee or a potentially there certificate issued exists presence or residues by it, which of flammable or explosive indicate that the substances; installations,
confined or limits the communication between the
concentrations of the atmosphere of the space
indicated in paragraph 8.4, after carrying out the
para 5.6 (PEC) and 9.1 Documentary. The employer complies when it presents Serious - subparagraphs c); e); n); o) and r) - documentary evidence that:
- It carries out work in confined spaces only with workers who are trained and authorised to do so;
- It has, where applicable, specific instructions for carrying out hot work, including the necessary safety measures and the conditions under which such work may not be carried out;
- It carries out the initial sampling of the concentrations in the atmosphere of the confined space, in accordance with the procedure referred to in paragraph 8.4 of this Standard;
- It compares the concentrations present in the confined space with the exposure limit values set out in NOM-010-STPS-1999, or the standards that replace it, provided that the measurement can be taken with direct-reading equipment, so as to verify that they are below the action level and allow the activities to be carried out safely, and
- It establishes the criteria for stopping the work when a condition arises that may create a risk.
confined, only with workers trained and
Has, where applicable, specific instructions for
para 5.6 (PEC, continued) and 9.3 Documentary. The employer complies when it presents - Serious - documentary evidence that it has procedures for the ventilation and/or purging of the confined space, in accordance with the risk analysis, the work to be carried out and the characteristics of that work, avoiding contamination of other areas of the workplace;
- It establishes the cases in which continuous ventilation is used,
- It states in the safety procedure determined in paragraph 8.2 of this Standard that ventilation by means of pure oxygen is prohibited, and
- It verifies that the concentration levels are below the action level, that the oxygen concentration is in the range of 19.5% to 23.5%, and that the flammability percentage is below 10% of the lower flammability and/or explosivity limit.
subparagraphs a); documentary evidence that for the
e); h) and j) technical control measures:
Determines the method to be usedpara 5.6 (PEC, continued 2) and 9.4 Documentary. The employer complies when it presents - Serious - documentary evidence that in Type II confined spaces, where it is not possible to maintain respirable atmospheres, it adopts the following administrative control measures:
- It reviews the duration of the activities and, where appropriate, reschedules the activities and/or redefines the duration of the work; and
- It has and follows up a respiratory protection programme containing the following elements:
- The record of the measurements of the concentrations inside the confined space;
- The supply of high-efficiency respiratory protective equipment and, where a high concentration or a concentration immediately dangerous to life and/or health exists, self-contained breathing apparatus or a respirator with an air supply line;
- The medical assessments of the personnel who need to use respirators to enter the confined space, making it possible to determine: o The fitness of the worker to use negative- and positive-pressure respirators, as applicable; o The ability of the worker to see and hear warnings, in accordance with the communication and/or alarm system provided, such as flashing lights, bells or sirens, among others; o The fitness of the worker to carry out the assigned tasks, and o The existence of any illness or abnormality that could hinder the use of the respiratory protective equipment or the performance of the activities inside the confined space;
- The criteria for selecting filters and cartridges, on the basis of NOM-116-STPS-2009 and/or the Mexican standards NMX-S-002-SCFI-2004 and NMX-S-054-SCFI-2013 on respirators, or the standards that replace them;
- The procedure for checking the fit and testing the tightness of the respirators;
- The instructions for the normal use of respirators and for their use in emergency situations;
- The instructions for checking the quality, quantity and flow of the air that shall be supplied to the worker, where self-contained breathing apparatus or respirators with an air supply line are used;
- storage, inspection, repair, replacement and final disposal of the respirators, and
- The training and information for the personnel who need to use respiratory protective equipment, including the limitations on its use.
5.7, 9.5 a) and Documentary. The employer complies when it presents
possible to maintain breathable atmospheres, adopts the measures
existence of a high concentration or a
respiratory or the performance of the
The instructions for maintenance, cleaning, disinfection, care,
repair, replacement and final disposal of the
para 9.6 (PEC) a) documentary evidence that:
- It designates a person in charge of the work and at least one attendant, and
- The person in charge of the work and the attendant(s) have the training required to perform the functions referred to in paragraphs 9.5 and 9.6 respectively.
5.7, 9.5 and 9.6 Physical. The employer complies when, on carrying out a Serious walkthrough of the workplace, it is verified that:
- The person in charge of the work in the confined space complies with the following:
- Ensures that the attendant is positioned and remains outside the space at all times while there is personnel in the confined space;
- Confirms before the activities begin, as applicable, that means of isolating energy, fluids, pressure, among others, are put in place through the use of tags and padlocks, and of equipment or devices, in accordance with NOM-004-STPS-1999 and NOM-029-STPS-2011, or the standards that replace them;
- Draws up and/or processes the authorisation to carry out the work in confined spaces, and cancels it once the work is finished or suspended;
- Verifies, as applicable, that the workers have the work plan and the authorisation referred to in paragraphs 8.5 and 8.6 of this Standard respectively, and that the authorisation is displayed at the entrance to the confined space;
- Supervises that the work is carried out safely, in accordance with this Standard;
- Ensures that the environmental conditions of the confined spaces are assessed while the work is being carried out, so as to verify that they allow the activities to be performed safely;
- Verifies that the safety procedures referred to in Chapter 8 of this Standard are available;
- Confirms that the tests or checks on the measuring equipment are carried out before its use;
- Checks that the resources for emergency response are available before work in the confined space begins, and
- Supervises that the emergency response and rescue plan is put into effect, and
- The attendant(s) for the work in the confined space comply with the following:
- Remains at all times, while the work is being carried out, outside the confined space, next to the entrance, in communication with the personnel performing the activities in the confined space;
- Stops the work or orders the evacuation of the confined space where a condition arises that may create a serious or imminent risk, or any other condition that puts the workers at risk or makes it harder for them to get out;
- Keeps a check on the number of workers entering the confined space and confirms that they all come out once the activities are finished;
- Ensures that the times of stay in the confined space are not exceeded, and
- Alerts the person in charge of the work should an emergency occur.
Interview. The employer complies when, on interviewing the person in charge of the work and the attendant(s), it is verified that: Serious
- The person in charge of the work in the confined space complies with the following:
- Ensures that the attendant is positioned and remains outside the space while there is personnel in the confined space;
- Confirms before the activities begin, as applicable, that means of isolating energy, fluids, pressure, among others, are put in place through the use of tags and padlocks, and of equipment or devices, in accordance with NOM-004-STPS-1999 and NOM-029-STPS-2011, or the standards that replace them;
- Draws up and/or processes the authorisation to carry out the work in confined spaces, and cancels it once the work is finished or suspended;
- Verifies, as applicable, that the workers have the work plan and the authorisation referred to in paragraphs 8.5 and 8.6 of this Standard respectively, and that the authorisation is displayed at the entrance to the confined space;
- Supervises that the work is carried out safely, in accordance with this Standard;
- Ensures that the environmental conditions of the confined spaces are assessed while the work is being carried out, so as to verify that they allow the activities to be performed safely;
- Verifies that the safety procedures referred to in Chapter 8 of this Standard are available;
- Confirms that the tests or checks on the measuring equipment are carried out before its use;
- Checks that the resources for emergency response are available before work in the confined space begins, and
- Supervises that the emergency response and rescue plan is put into effect, and
- The attendant(s) for the work in the confined space comply with the following:
- Remains at all times, while the work is being carried out, outside the confined space, next to the entrance, in communication with the personnel performing the activities in the confined space;
- Stops the work or orders the evacuation of the confined space where a condition arises that may create a serious or imminent risk, or any other condition that puts the workers at risk or makes it harder for them to get out;
- Keeps a check on the number of workers entering the confined space and confirms that they all come out once the activities are finished;
- Ensures that the times of stay in the confined space are not exceeded, and
- Alerts the person in charge of the work should an emergency occur.
times, while there is personnel in the space
para 5.8 (PEC) Physical check. The employer complies when, during a walkthrough of the workplace, it is verified that it provides lighting inside the confined spaces, appropriate to the activities to be performed, that allows the work to be carried out safely, by means of portable lamps or equipment and/or lighting systems.
para 5.9 (PEC) Documentary. The employer complies when it presents - Serious - documentary evidence that it provides workers with the personal protective equipment required, on the basis of the classification of the confined space, the risk analysis and the activity to be performed, in accordance with NOM-017-STPS-2008, or the standards that replace it.
para 5.10 (PEC) and 10 Documentary. The employer complies when it presents - Serious - documentary evidence that:
- It has an emergency response and rescue plan that provides for the rescue of workers who may be injured, and that includes the necessary equipment;
- The emergency response and rescue plan takes into account the emergency situations that may arise during the work in the confined space, identified in the risk analysis, and
- The emergency response and rescue plan contains at least the following:
- The scope of the plan, in accordance with the work carried out, the type of confined space and the risk analysis;
- The conditions under which emergency and rescue personnel, both internal and external, may or may not enter the confined space;
- The person responsible for putting the plan into effect;
- The human and material resources for carrying it out, stating the names of the workers designated and trained to apply the plan, and the function assigned to each of them;
- The training required of the workers in relation to the content of the plan, taking into account the type of confined space;
- The personal protective and rescue equipment required for emergency response;
- The inventory of the material resources required and available to deal with emergency situations, and
- The procedures for: o Raising the alarm should an emergency occur; o Internal and external communication should an emergency occur, together with the directory of the emergency services (fire brigade, hospitals and rescue) and, where applicable, the directory of the centres for information on the handling of chemical substances in emergencies; o Stopping the operation of the machinery and equipment; o Suspending the activities; o Rescuing injured workers; o Evacuating the workers who are at risk, according to the emergency situation(s) that may arise, including workers and persons with disabilities who do not work in the confined space and who are presumed to be at risk; o First aid, and o The elimination of the risks after the emergency, where applicable.
accordance with the situation(s) of
para 5.11 (PEC) and 11 Documentary. The employer complies when it presents documentary evidence that: The documentary evidence for compliance with this obligation consists of the certificates of occupational competence or skills.
- It provides information and training to the workers who perform activities in confined spaces, in accordance with the work to be carried out, its classification and the result of the risk analysis;
- The information provided to the workers takes into account the result of the risk analysis of each of the confined spaces;
- The workers involved in performing activities in confined spaces are provided with training, with emphasis on risk prevention, on the basis of the type of confined space and the tasks assigned, and on the emergency response and rescue plan;
- The training and instruction provided to the workers consist of theoretical instruction, practical training and assessment of the knowledge and skills acquired, and take into account the following:
- The content of this Standard, with emphasis on the application of the safety measures;
- The hazards and risks present in the confined space;
- The risks arising from the properties of the chemical substances present in the confined space;
- The effects that exposure to the chemical substances may cause and the corresponding physical and health hazards;
- How to work safely, the safety procedures and the authorisations required to carry out the activity;
- The correct way to operate, check and, where applicable, store the ventilation equipment installed or used for work in confined spaces;
- The respiratory protection programme, where applicable;
- The use of respiratory protective equipment, including the limitations on its use;
- The correct use of personal protective equipment, in accordance with NOM-017-STPS-2008, or the standards that replace it;
- The use, handling and reading of personal measuring equipment, and
- The application of the emergency response and rescue plan, including drills on the possible emergency situations that may arise, foreseen in the risk analysis;
- In addition to paragraphs 11.2 and 11.3, the person in charge and the attendant for work in confined spaces shall be trained, instructed and assessed on the following subjects:
- The procedure for the confined space;
- The assessment of the concentrations obtained;
- The cases in which the activities shall be suspended, and
- The specific actions they are to carry out for emergency response and rescue;
- The workers who are members of the rescue team are trained specifically in the emergency response and rescue plan, with emphasis on the use of personal protective and rescue equipment and on the application of the procedures referred to in that plan, and
- The training and instruction are reinforced at least once a year, or sooner where any of the following circumstances arises:
- New tools or equipment are introduced, or the conditions inside the confined space are altered;
- An incident or accident has occurred;
- Unsafe operation of the equipment becomes evident, or
- The most recent assessment of the workers who perform activities in confined spaces so suggests.
confined spaces are provided training, with
The hazards and risks present in the space
rescue, including the carrying-out of drills
sampling of the concentrations of the atmosphere of the space
para 5.11 (PEC, continued) and 11.7 Records. The employer complies when it presents evidence that it keeps the record of the training and instruction provided to workers, which contains at least the following:
- The name and position of the workers to whom it was provided;
- The date on which the training was provided;
- The subjects taught, and
- The name of the instructor and, in the case of training agents external to the workplace, the registration number with the Ministry of Labour and Social Welfare.
para 5.12 (PEC) Documentary. The employer complies when it presents. This provision is met by the declaration of conformity, in accordance with paragraph 13.3 of this Standard, or else by means of an opinion issued by a verification unit stating that the third party complies with this Standard.
documentary evidence that it complies by means of verifies that contractors comply a document that with the provisions of this Standard, contains the aspects when the employer engages the services to be verified indicated of third parties to perform work in in the procedure confined spaces. for the evaluation of
accordance with
the provisions of thepara 5.13 (PEC) Records. The employer complies when it presents evidence that it keeps the records of the personnel authorised to carry out work in confined spaces; of their entry into and exit from such spaces; their time spent inside, and the sampling and/or monitoring of the atmosphere.
para 13.4 For the selection of workers to be interviewed, for the purpose of verifying compliance with the provisions of this conformity assessment procedure, the sampling criterion contained in Table 2 below shall apply:
Table 2 Random selection sampling
Total number of workers Number of workers to be interviewed
1-15 1
16-50 2
51-105 3
More than 105 1 for every 35 workers up to a maximum of 15
para 13.5 The documentary evidence or records referred to in this Standard may be presented in printed form or on magnetic media, and shall be kept for at least one year.
14. Enforcement
Enforcement of compliance with this Official Mexican Standard is the responsibility of the Ministry of Labour and Social Welfare.
15. Bibliography
para 15.1 A Guide to Safety in Confined Spaces, National Institute for Occupational Safety and Health, NIOSH, July 1987. U.S. Department of Health, Education and Welfare.
para 15.2 Confined Spaces Guideline, Health and Safety Guidelines. Ministry of Labour, July 2011. Ontario, Canada.
para 15.3 Manual de Seguridad en el Trabajo. Fundación MAPFRE, 2011. Spain.
para 15.4 NIOSH Pocket Guide to Chemical Hazards, National Institute for Occupational Safety and Health, NIOSH, September 2007. U.S. Department of Health and Human Services.
para 15.5 Norma Regulamentadora No. 33: NR-33 Segurança e Saúde nos Trabalhos em Espaços Confinados, Ministério do Trabalho e Emprego. Brazil.
para 15.6 NTP 223: Trabajos en recintos confinados, Instituto Nacional de Seguridad e Higiene en el Trabajo, Ministerio del Trabajo y Asuntos Sociales. Spain.
para 15.7 Reglamento Federal de Seguridad y Salud en el Trabajo, published in the Official Gazette of the Federation on 13 November 2014. Mexico.
para 15.8 Safe work in confined spaces, Confined Spaces Regulations 1997, Approved Code of Practice, Regulations and Guidance. Health and Safety Executive, 2009. Great Britain.
para 15.9 Working in Confined Spaces. Criteria for a Recommended Standard…, National Institute for Occupational Safety and Health, NIOSH, December 1979. U.S. Department of Health, Education and Welfare.
16. Correspondence with international standards
This Official Mexican Standard does not correspond to any international standard, as no such reference existed at the time it was drafted.
TRANSITORY PROVISIONS
FIRST. This Official Mexican Standard shall enter into force three months after its publication in the Official Gazette of the Federation (DOF). SECOND. During the period established in the preceding article, employers shall comply with the specific provisions for performing work in confined spaces contained in Official Mexican Standards NOM-005-STPS-1998, Concerning the safety and hygiene conditions in workplaces for the handling, transport and storage of hazardous chemical substances, and NOM-027-STPS-2008, Welding and cutting activities - Safety and hygiene conditions, or they may instead comply with NOM-033-STPS-2015, Safety conditions for work in confined spaces. Where they choose to comply with NOM-033-STPS-2015, Safety conditions for work in confined spaces, the employers concerned shall inform the labour authority of this decision in advance and may request an advisory and technical assistance inspection to implement compliance, under articles 18 and 19 of the General Regulation on Labour Inspection and the Application of Sanctions, without incurring sanctions for non-compliance with the Standard in force. THIRD. From the date this Standard enters into force, paragraph 8, subparagraph g), item 5), and paragraph 9.10 of NOM-005-STPS-1998, Concerning the safety and hygiene conditions in workplaces for the handling, transport and storage of hazardous chemical substances, published in the Official Gazette of the Federation on 2 February 1999, as well as paragraphs 9.2 and 10.5 of NOM-027-STPS-2008, Welding and cutting activities - Safety and hygiene conditions, published in the Official Gazette of the Federation on 7 November 2008, shall cease to have effect. Mexico City, Federal District, on the thirtieth day of July of two thousand and fifteen. The Secretary of Labour and Social Welfare, Jesus Alfonso Navarrete Prida. Signed.