NOM-009-STPS-2011, Safety conditions for work at height

That on 31 August 2010, in compliance with the provisions of article 46, section I, of the Federal Law on Metrology and Standardisation, the Ministry of Labour and Social Welfare (Secretaría del Trabajo y Previsión Social) submitted to the National Advisory Committee for Standardisation on Occupational Safety and Health (Comité Consultivo Nacional de Normalización de Seguridad y Salud en el Trabajo) the Preliminary Draft Amendment to this Official Mexican Standard, and that the Committee considered it correct and agreed that it be published as a Draft in the Diario Oficial de la Federación; That, to comply with articles 69-E and 69-H of the Federal Law on Administrative Procedure, the corresponding Preliminary Draft was submitted for consideration to the Federal Commission for Regulatory Improvement (Comisión Federal de Mejora Regulatoria), which issued a favourable opinion on it; That on 22 October 2010, in compliance with the Agreement establishing the organisation and Operating Rules of the National Advisory Committee for Standardisation on Occupational Safety and Health, and with the provisions of article 47, section I, of the Federal Law on Metrology and Standardisation, the Draft Amendment to Official Mexican Standard NOM-009-STPS-1999, Suspended access equipment - Installation, operation and maintenance - Safety conditions, to become PROY-NOM-009-STPS-2010, Safety conditions for work at height, was published in the Diario Oficial de la Federación so that, within the 60 calendar days following that publication, interested parties could submit their comments to the Committee; That, having received comments from eight petitioners, the Committee proceeded to study them and resolved on them in due course, this department publishing the respective responses in the Diario Oficial de la Federación of 24 March 2011, in compliance with the provisions of article 47, section III, of the Federal Law on Metrology and Standardisation; That, as a result of incorporating the comments submitted on the Draft Amendment to Official Mexican Standard NOM-009-STPS-1999, Suspended access equipment - Installation, operation and maintenance - Safety conditions, to become PROY-NOM-009-STPS-2010, Safety conditions for work at height, as well as of the final review of the draft itself, various amendments were made to provide clarity, consistency and legal certainty regarding the provisions applying in workplaces, and That, in view of the foregoing considerations, and since the National Advisory Committee for Standardisation on Occupational Safety and Health granted its approval, the following is issued: OFFICIAL MEXICAN STANDARD NOM-009-STPS-2011, SAFETY CONDITIONS FOR WORK AT HEIGHT

Reference Guide I Minimum content of the instructions, manuals or procedures for the installation, operation and maintenance of suspended equipment for work at height Reference Guide II First-aid kit

To establish the minimum safety requirements for the prevention of occupational risks arising from work at height.

This Standard applies throughout the national territory and to any place where work at height is performed.

For the correct interpretation of this Standard, the following Official Mexican Standards in force, or those replacing them, shall be consulted:

3.1 NOM-004-STPS-1999, Protection systems and safety devices for machinery and equipment used in workplaces.

3.2 NOM-017-STPS-2008, Personal protective equipment - Selection, use and handling in workplaces.

3.3 NOM-026-STPS-2008, Safety and health colours and signs, and identification of hazards from fluids conveyed in pipelines.

3.4 NOM-029-STPS-2005, Maintenance of electrical installations in workplaces - Safety conditions.

For the purposes of this Standard, the following definitions are established:

4.1 Energy absorber; shock absorber: The component of the personal fall-arrest system designed to dissipate the kinetic energy generated during a fall, and which limits the forces applied to the system, to the anchorage device and to the user.

4.2 Scaffold: Any platform, with its structural, support and anchoring elements, temporarily raised, supported or suspended, that is used to perform work at height. It includes, by way of illustration, the following types: a) Single-point: One supported by cables at a single anchor point; b) Two-point: One supported by cables at two anchor points; c) Multi-point: One supported by cables at three or more anchor points, and in which the platform modules are not articulated with one another; d) Continuous articulated: One made up of articulated modules supported by cables at three or more anchor points; e) Temporary suspended: One installed temporarily on a building or structure to carry out specific tasks, supported by one or more anchor points, which shall be assembled before being used at the worksite, and dismantled or removed on completion of the tasks, and f) Multi-span: One formed by two or more levels mounted vertically.

4.3 Harness; full-body harness: The personal protective equipment that fits around the user's torso and thighs, made up of components such as flexible straps, buckles, adjustment mechanisms, fittings and metal rings, and used mainly in fall-arrest systems to support the user.

4.4 Labour authority; labour inspection authority: The competent administrative units of the Ministry of Labour and Social Welfare that carry out inspection functions in respect of occupational safety and health, and the corresponding units of the federative entities and the Federal District that act in support of them.

4.5 Sliding-type fall arrester: The device designed to attach to a vertical rail or vertical lifeline, and to slide up and down in response to ascending movements, and which locks automatically in response to the sudden movement of a fall.

4.6 Safety cable (on suspended scaffolds): The backup cable that is rigged with the fall-arrest device, but which does not normally support the suspended load.

4.7 Suspension cable: The cable that supports the suspended load.

4.8 Total load (in collective-use systems for work at height): The total weight to which the supports of the suspension system will be subjected, comprising the weight of the workers, equipment, tools and work materials, as well as of each and every component of the system itself, such as the platform, winches, cables, among others.

4.9 Connector: The device that allows the physical joining of two elements of a personal fall-arrest system.

4.10 Counterweights: The weights attached to the suspension support to counteract the overturning moment.

4.11 Deployment: The action of the energy absorber permanently extending to dissipate the energy applied to it during a fall.

4.12 Safety devices (in suspended systems): The elements that prevent the development of a hazardous phase, such as failure of winches, suspension cables, supports and other suspension devices. The types of devices that normally occur are: a) Power-failure descent device: Allows the manual descent of a powered platform; b) Fall-arrest device: Stops the descent of the platform by acting directly on the safety cable; c) Tilt-detection device: Indicates the longitudinal slope of the platform when it exceeds a preset angle; d) Secondary device: Stops the descent of the platform in the event of suspension cable failure or winch failure, and e) Secondary brake device: Stops the descent of the platform by acting directly on the drum, the traction pulley or the end of the drive shaft.

4.13 Suspended access equipment (for building maintenance): The equipment designed or selected to be permanently installed on a specific structure or building. It is made up of a suspended platform and an upper support. It is generally a unit with a trolley and winch, which operates on rails or on another suitable surface, such as a concrete track or monorail, with a transverse trolley or other upper suspension systems.

4.14 Movable ladder; portable ladder; hand ladder: The portable apparatus consisting of two parallel or slightly converging members, joined at intervals by rungs, and used to raise or lower a person from one level to another.

4.15 Stabiliser: The arm-shaped element, on elevating work platforms, that acts as a support to give the elevating work platform greater stability.

4.16 Lifeline: The segment of flexible material that, together with an energy absorber, is used as a linking or connecting element in the event of a worker falling.

4.17 Horizontal lifeline: The flexible line under tension whose ends are attached to anchor points, and along which a connector of a personal fall-arrest system can slide.

4.18 Vertical lifeline: The flexible line installed temporarily or permanently, suspended or under tension, to which a sliding-type fall arrester can be connected.

4.19 Winch: The hoisting, lowering and traction device that raises or lowers the platform, basket or bosun's chair in a suspended system.

4.20 Monorail: The rail set on the perimeter of the building at roof level, to support and guide the transverse trolley.

4.21 Reference level: The surface considered as the base for measuring the height of the working plane.

4.22 Employer: The individual or legal entity on whom the responsibility falls for carrying out work at height, through the services of one or more workers under their charge.

4.23 Work platform; support platform: The surface of the scaffold or elevating work platform that supports the workers, equipment, tools and materials, and from which activities or work at height are carried out.

4.24 Lateral protection; guardrail: The guard fitted around the perimeter of a work platform or in areas where there is a risk of falling from height.

4.25 Anchor point: The element with sufficient strength for fixing winches, suspension cables, safety cables and other suspension, support or fall-arrest devices, and which may be located or installed on buildings, suspended scaffolds, elevating work platforms, among others, where work at height is performed.

4.26 Safety net: The mesh of flexible material arranged to stop the fall of one or more persons, and whose design prevents them from being thrown clear of the net. Nets may also be used as protection against falling objects.

4.27 Personal fall-arrest system; fall-arrest system: The system that minimises the forces at the moment of arresting a fall from height; controls the total distance travelled during the fall, preventing collision with the floor or any other obstacle, and enables the person to be kept in a suitable position after the fall for rescue purposes.

4.28 Suspension system: The set of elements of a suspended scaffold or other similar system, which generally comprises the supports and the suspension ropes or cables.

4.29 Personal systems for work at height: Those for personal use, employed to suspend or support a worker in activities involving a risk of falling from height. They also include those used for the prevention of falls from height and for arresting them should they occur. They comprise, among others, those known as restraint, positioning, controlled ascent and/or descent, and fall-arrest systems.

4.30 Suspension-cable restraint systems: The devices of suspended equipment, located horizontally on the wall of the building, fitted with a rope and ring coupled to each of the suspension cables during the descent movement, and uncoupled during ascent.

4.31 Suspension support; anchorage: The fixed or movable structure that allows the suspension and safety cables to be anchored.

4.32 Drum: The hollow cylinder of smooth or grooved metal, whose ends are flanked by discs and on which the cable is wound.

4.33 Work at height: Maintenance, installation, demolition, operation, repair, cleaning and other activities carried out at heights greater than 1.80 m above the reference level. It also includes the risk of falling through openings in working surfaces, such as boreholes, shafts, wells and vertical tunnels.

4.34 Transverse trolley: The wheeled carriage designed to move transversely along a monorail from which a platform is suspended.

4.35 Suspension beam: The static element for supporting the suspended access equipment, whose stability is ensured by counterweights.

5.1 Have an analysis of the prevailing conditions in the areas where work at height will be carried out, before it is performed, to identify the existing risk factors.

5.2 Have available the instructions, manuals or procedures for the installation, operation and maintenance of the systems or equipment used in work at height, drawn up in the Spanish language. Such instructions, manuals or procedures shall be prepared on the basis of the manufacturer's instructions.

5.3 Provide written authorisation to workers performing work at height using tower- or structure-type scaffolds, suspended scaffolds and elevating work platforms, as determined in paragraph 7.2 of this Standard, which shall be granted once it has been verified that the required safety measures have been applied.

5.4 Comply with the general safety measures and safety conditions set out in Chapters 7 to 13 of this Standard for carrying out work at height using personal systems for work at height, tower- or structure-type scaffolds, suspended scaffolds, elevating work platforms, portable ladders and safety nets.

5.5 Supervise compliance with the safety measures set out in the instructions, manuals or procedures for the installation, operation and maintenance of the systems or equipment used in work at height, as well as with the general safety measures and safety conditions established in this Standard.

5.6 Avoid or interrupt activities at height when unsafe conditions are detected in the systems or equipment used for this work, or when weather conditions exist that endanger workers.

5.7 Establish and apply an inspection and maintenance programme for the systems or equipment used to perform work at height, in accordance with paragraph 7.14 of this Standard and with the manufacturer's instructions.

5.8 Keep records of the inspections and of the preventive and corrective maintenance carried out on the systems or equipment used to perform work at height, which shall be kept for at least one year.

5.9 Provide workers performing work at height with at least one personal fall-arrest system, in accordance with paragraph 8.4 of this Standard, as well as with the personal protective equipment referred to in Chapters 7 to 13 of this Standard, or with that required on the basis of the risk factors identified in the analysis of the prevailing conditions of the area, in accordance with the provisions of NOM-017-STPS-2008, or those replacing it.

5.10 Carry out medical examinations of workers who will perform work at height, in accordance with Chapter 14 of this Standard.

5.11 Have an emergency response plan in place, in accordance with Chapter 15 of this Standard, arising from the performance of work at height.

5.12 Have a first-aid kit containing the manual and the treatment materials needed to deal with possible emergencies, identified according to the risks to which workers are exposed and the activities they perform.

5.13 Provide training, instruction and information to workers who will be involved in performing work at height, on the basis of the provisions of Chapter 16 of this Standard, as well as regarding implementation of the emergency response plan referred to in Chapter 15 of this Standard.

5.14 Supervise that contractors comply with the provisions of this Standard, when the employer engages the services of third parties to perform work at height.

5.15 Produce to the labour authority the documents that this Standard requires the employer to prepare and hold, when so requested by that authority.

6.1 Take part in the training provided by the employer for the safe performance of work at height and for implementing the emergency response plan.

6.2 Know and comply with the safety measures established by the employer or contractor in the instructions, manuals or procedures for performing work at height safely.

6.3 Inform the employer or contractor of any unsafe condition and/or unsafe act observed during work at height, or of any wear, damage, deterioration, malfunction or other anomaly detected in the systems, equipment or their components used to perform this type of activity, so that the relevant corrective measures are taken and it is verified that there is no risk in their use.

6.4 Use the personal protective equipment provided to them, on the basis of the risks to which they are exposed.

6.5 Attend and undergo the medical examinations indicated by the employer, and inform the employer of any health impairment or acrophobia (fear of heights) that could compromise their own safety or that of third parties during the performance of work at height.

The following shall be complied with when performing work at height:

7.1 Fit, at the edges of roofs, terraces, viewing platforms, galleries or elevated fixed structures, as well as at openings such as boreholes, shafts, wells and vertical tunnels: fixed barriers or lateral or perimeter protection, or safety nets for collective protection against falls from height, in accordance with Chapter 13 of this Standard, among other preventive elements, or otherwise provide workers with personal systems for work at height, in accordance with Chapter 8 of this Standard.

7.2 Carry out work at height only with personnel who are trained and authorised by the employer. The authorisations shall contain at least the following: a) The name of the authorised worker; b) The type of work to be carried out and the area or place where the activity will be performed; c) The safety measures to be applied for the work at height to be performed, and the risk factors identified in the analysis of the prevailing conditions of the area where it will be carried out; d) The date and time the activities begin, and the estimated duration, and e) The name and signature of the employer or of the person designated to grant the authorisation.

7.3 Inspect the system or equipment before use, in accordance with the manufacturer's instructions, for possible wear, damage, deterioration, malfunction or other anomalies. Defective components shall be removed from service and identified to prevent their use, if their strength or performance is affected. Any component that needs to be replaced shall be replaced only with another original component or one authorised by the manufacturer in the maintenance manual it provides with the system.

7.4 Supervise that work at height is carried out in accordance with the general safety measures and safety conditions set out in Chapters 7 to 13 of this Standard.

7.5 Use a personal fall-arrest system for work at height, in accordance with paragraph 8.4 of this Standard.

7.6 Verify that the rated load capacity of the system or equipment in use is not exceeded under any circumstances, in accordance with the operating instructions or manual and the manufacturer's specifications.

7.7 Consider the additional risks generated by the presence of heat sources - such as welding and cutting operations -, moisture, acids, oil, grease, dust, corrosive environments or extreme temperatures, among others; assess their effect on the system in use, and adopt preventive measures for personnel performing work at height in the presence of high ambient temperatures, such as hydration, skin protection and/or work breaks.

7.8 Prohibit the use of metal cables where there is an electrical risk.

7.9 De-energise or relocate electrical lines located at the place where work at height will be carried out and that pose a risk to workers, in accordance with NOM-029-STPS-2005, or those replacing it, or, where this is not possible, maintain at all times the safety distances to such lines, in accordance with Table 1 below: Table 1 Safety distances to energised electrical lines Voltage (phase to phase) Minimum safety distance (V) (m) Up to 50 000 3.10 73 000 3.33 85 000 3.45 115 000 3.75 140 000 4.00 230 000 4.90 400 000 6.60 600 000 8.60

7.10 Apply, when working near energised lines, even where the safety distances referred to in paragraph 7.9 of this Standard are maintained, the following safety measures: a) Take precautions to avoid accidental contact with energised lines when handling long conductive objects, such as rods, pipes, cables, tools, among others; b) Fit protection such as insulating tape or blankets on the electrical lines, appropriate to the voltage carried by them, applied by personnel trained in handling energised electrical lines, and c) Use personal protective equipment, consisting at least of a helmet with a chin strap, and dielectric footwear and gloves, appropriate to the electrical voltage of the energised lines.

7.11 Protect ropes or cables where they pass over sharp edges or corners, or over rough surfaces, that could have a cutting effect or cause excessive wear from friction, using materials that prevent these risks.

7.12 Demarcate the zone or area at ground level where work at height will be performed, by cordoning it off and signposting it, the latter on the basis of NOM-026-STPS-2008, or those replacing it, to prevent persons from remaining in or passing through that zone or area.

7.13 Avoid or interrupt activities at height when weather conditions are detected that involve risks to workers, such as heavy rain, electrical storms, snowfall and sustained strong winds, in accordance with the characteristics of the system or equipment used and the manufacturer's specifications.

7.14 Subject the system or equipment used to an annual inspection, or with the frequency indicated by the manufacturer, whichever is shorter, to ensure that it is in optimum safety and operating condition. Such inspection shall be carried out by personnel trained and instructed for that purpose. In the case of systems used in environments with extreme conditions or conditions harmful to them, inspections shall be scheduled more frequently.

7.15 Keep a record of the inspections and maintenance carried out on the systems or equipment, in which at least the following shall be recorded: a) The general details of the system or equipment, such as make, model and serial number or other individual identification; b) The dates of inspections and maintenance actions; c) The observations resulting from the inspections carried out on the system or equipment; d) The preventive and corrective actions taken, such as repairs, replacements, withdrawal from service, destruction, among others; e) The identification of the worker or workers responsible for the repair, and f) The identification of those responsible for releasing it for use.

8.1 General requirements

8.1.1 It shall be supervised, at all times when performing work at height, that the personal system for work at height is used in accordance with the manufacturer's instructions.

8.1.2 It shall be verified that the personal systems and their subsystems and components, as applicable, bear the official mark of a certification body, accredited and approved under the Federal Law on Metrology and Standardisation, certifying their compliance with the Official Mexican Standards or, in the absence of these, with the relevant Mexican standards.

8.2 Restraint systems

8.2.1 Restraint systems shall be used only to limit the distance a worker can travel towards any hazardous edge where a fall could occur. This type of system shall not be used for fall arrest.

8.2.2 When using restraint systems, the approach distance to the fall-risk zone (edges) shall be limited to no less than 1.20 m. For this purpose, a full-body harness or safety belt shall be used, connected by a lifeline to a fixed point or device that limits the worker's proximity to that zone. Figure 1 illustrates the use of this type of system. Figure 1 Use of personal restraint systems

8.3 Positioning and controlled ascent/descent systems

8.3.1 Positioning and controlled ascent/descent systems (see Figure 2) shall meet, as applicable, the following: Figure 2 Positioning and controlled ascent/descent systems a) Use positioning systems only to keep the user positioned at their work point. This type of system shall not be used for fall arrest; b) Use an element attaching the worker to the controlled ascent/descent device, such as a rope, strap or connector, to allow the work to be carried out in a stable manner with both hands free; c) Use a tool belt for the secure attachment of tools and other work items, thereby preventing them from falling accidentally, and d) Use, as applicable, tool lanyards or cords, which are usually in turn tied to a wristband or belt, to prevent the tool from falling if it is accidentally released while in use.

8.4 Personal fall-arrest systems

8.4.1 The use of personal fall-arrest systems shall be mandatory when performing work at height on: a) Edges of roofs, terraces, viewing platforms, galleries or elevated fixed structures, as well as at openings such as boreholes, shafts, wells and vertical tunnels, where fixed barriers or lateral or perimeter protection cannot be fitted, or personal restraint systems are not used; b) Elevated fixed structures where safety nets cannot be fitted; c) Tower- or structure-type scaffolds, above 3.5 m; d) Suspended scaffolds or elevating work platforms, and e) Portable ladders, above 3.5 m from the reference level.

8.4.2 The personal systems used for fall arrest shall be made up, as applicable to the system in use, of at least: a) A full-body harness; b) A lifeline; c) Connectors; d) Energy-absorbing devices, and e) Anchor points or anchorage devices.

8.4.3 When using personal fall-arrest systems, the following shall apply: a) Install and assemble the system in accordance with the procedure drawn up for that purpose, in line with the manufacturer's instructions, and only by personnel trained and authorised by the employer for this purpose; b) Limit the fall distance to the minimum possible; c) Position the anchor point in accordance with the manufacturer's instructions; it shall not be located below the working plane. An anchor point may be a column, girder, beam or other structural element of a building; a fitting fixed to any of these elements, or a device built into a basket, arm or work platform, on a suspended scaffold or elevating work platform; d) Limit the total mass - the worker's mass plus tools - to that specified by the manufacturer of the system in use; e) Select or install anchor points or anchorage devices, respectively, that can withstand the arrest force generated during a fall. The anchor point or anchorage device shall never be selected below the worker's support level; f) Ensure that there is clear space along the path of a possible fall, to prevent the worker from striking obstacles; g) Inspect the system before use and in accordance with the manufacturer's instructions, checking at least the following aspects: 1) That there is no corrosion or other degradation of the materials in its metal parts; 2) That there is no deformation, cracking, rupture or other similar damage to the buckles, rings, hooks, snap hooks and carabiners; 3) That the opening, closing and locking of all connectors operate correctly; 4) That the ropes, straps and cables show no ruptures, fraying, unravelling, unstitching, wear, kinking, corrosion or burns, and 5) That the labels and markings are legible; h) Identify and remove from service any defective components of the system or equipment where their strength or performance is affected, to prevent their use; i) Replace any subsystem or component only with another original component or one authorised by the manufacturer in the maintenance manual it provides with the system; j) Carry out repairs in accordance with the manufacturer's instructions, and only by personnel trained and authorised by the employer; k) Use connectors such as snap hooks, hooks, carabiners and other attachment elements that remain automatically closed and locked, to prevent them from opening or releasing accidentally. These shall be disconnected only by the worker performing at least two consecutive deliberate actions (double locking). Connectors shall not be connected to other objects that are incompatible in shape or dimensions and that would compromise their safe operation; l) Use synthetic-fibre ropes and straps or metal cable for lifelines, safety cables and other components subject to loading; m) Take into account, when installing the system: 1) The possible effect of rope elongation; 2) The pendulum effect; 3) The presence of energised electrical lines, and 4) The deflection of a horizontal lifeline (see Figure 3); Figure 3 Horizontal lifelines n) Install the system so that the maximum free-fall distance, before the energy absorber activates, is up to 1.8 m or 3.5 m, depending on the type of energy absorber incorporated in the system; o) Avoid assembling subsystems or components from different manufacturers that are incompatible; p) Mark or identify a system that has been activated to arrest a fall, and q) Prohibit the reuse of a system that has been activated to arrest a fall, unless expressly permitted by the manufacturer, whether as a whole or for any of its components or subsystems.

8.4.4 When using systems based on horizontal lifelines, the following shall apply: a) Install and operate the system in accordance with the manufacturer's specifications; b) Verify that the supports have the required strength; c) Ensure the horizontal cable is correctly tensioned, and d) Control the total available fall distance, taking into account the deployment distance of the energy-absorbing device and the deflection or catenary (the curve formed in a rope or cable when held at its ends) that the horizontal line would form.

8.4.5 When using systems based on vertical lifelines, the following shall apply: a) Install and operate the system in accordance with the manufacturer's specifications; b) Provide each worker with an independent vertical lifeline, where the system is not designed to support more than one worker (see Figure 4); Figure 4 Vertical lifelines c) Ensure that the upper support and, where applicable, the lower support meet the required strength, and that the cable is correctly tensioned, as applicable, and d) Test, before each use, the operation of the sliding-type fall arrester, in fall-arrest systems consisting of vertical rails or lines used on ladders or other structures.

8.4.6 When using systems based on retractable lifelines, the following shall apply: a) Install and operate the system in accordance with the manufacturer's specifications; b) Comply with the provisions set out in paragraph 8.4.3 of this Standard; c) Avoid obstructions along the path of a possible fall, and prevent the lifeline from becoming entangled or crossed with those of other workers; d) Take into account the locking speed, in accordance with the manufacturer's instructions; e) Avoid performing work at sites where the lifeline could be in contact or friction with sharp edges, extreme heat, corrosive substances or environments, moving machinery, among others, and f) Prevent the lifeline from being connected to other components to extend its length.

9.1 When installing tower- or structure-type scaffolds, the following shall be complied with: a) Install and assemble the scaffold using the procedure drawn up for that purpose, in accordance with the manufacturer's instructions, and only by personnel trained and authorised by the employer for this purpose; b) Test that the scaffold and its components can withstand at least four times the maximum load to which they will be subjected, taking into account the weight of personnel, materials and tools to be used; c) Install the scaffold on: 1) Its base plates, to provide greater stability, or on castors fitted with a locking mechanism, which shall be released only when the scaffold needs to be moved for relocation; 2) Firm, stable surfaces of sufficient strength, so as to prevent any possible failure, rupture, subsidence or accidental displacement, and 3) Level surfaces, and where these are not level, use the plumbing, stabilising and levelling means indicated by the manufacturer; d) Provide the scaffold with a ladder or other similar means of safe access, which shall: 1) Be located within the body of the scaffold or form part of it without affecting its stability; 2) Have a minimum width of 40 cm; 3) Extend 90 cm above the floor of the work platform and be secured against any bending or lateral movement, where they are movable; 4) Be continuous, with no improvised devices used to increase their height, and 5) Have a rest platform located at intervals not exceeding 6 m (see Figure 5); Figure 5 Tower- or structure-type scaffolds e) Be fitted with guardrails at least 90 cm high and a mid-rail on the open sides and at the ends, where they are 1.8 m or more above the floor or above the level below; f) Have a toe-board at least 15 cm high, flush with the platform; g) Use support platforms that meet the following: 1) Be in safe and operational condition, with no cracks, fissures, knots or other defects or damage that compromise safety in use; 2) Have complete planks or units, with a minimum width of 45 cm, covering the entire scaffold area. Where there are gaps between the planks or units, they shall not exceed 2.5 cm; 3) Have planks at least 5 cm thick, reinforced where applicable with a metal frame and crosspieces to increase their strength and reliability, and 4) Have means of immobilising them, to prevent them from shifting or moving accidentally in any way. If the immobilising element consists only of stops to prevent the plank from sliding, it shall project at least 10 cm from the scaffold; h) Verify that there are no dents, cracks, deformations or corrosion on its tubes and other metal elements; i) Have the threads of nuts and bolts, clamps and safety pins in safe and operational condition, and not use nails, rods or wire as substitutes; j) Inspect the scaffold before each use and after any incident, to check the safety and operating condition of each of its components, and have trained personnel replace or repair any that show damage or deterioration; k) Prohibit workers from remaining on mobile scaffolds while they are being relocated, and take special precautions to keep the scaffold stable while it is being moved; l) Avoid carrying out activities above the scaffold that expose workers to possible falling objects, or provide protection against this risk and use a protective helmet; m) Prevent scaffolds from being assembled, used or moved in such a way that they, or any conductive material on them, could come into contact with energised electrical lines. Where it is necessary to work near such lines, the provisions set out in paragraph

7.9 of this Standard shall be observed; n) Verify that the ratio of the shorter side of the scaffold base to the maximum height is no greater than 1:4; o) Tie the scaffold at every 4 m of height, in cases where the base-to-height ratio set out in the preceding item cannot be met; p) Avoid using trestle-type ladders as a support for planks used as scaffolding; q) Avoid any alteration to scaffolds that could affect safety in use. Any modification to the design, installation, operation or maintenance shall be endorsed in writing by the manufacturer and authorised by the employer; r) Keep the surface of the scaffold's support platform free of aggressive chemical products, and of substances such as soapy solutions, oil, grease, paint, mud or others that could make it slippery or create any other risk to workers; s) Maintain a minimum clear height of 2.5 m on pedestrian routes. On vehicle routes, the clear height shall be at least 4.5 m and the scaffold shall be kept at least 80 cm away from the vehicle route; t) Maintain a minimum distance of 60 cm from the traffic area to the scaffold, and of 90 cm in places where materials are stored; u) Position the scaffold so that it does not interfere with fire alarms, electrical installation boxes or hydrants, among others, where it is not possible to make the necessary adjustments to the scaffold so that such elements continue to fulfil their function, and v) Fit a tag (see Figure 6) indicating its condition, which shall: Figure 6 Examples of information tags on the condition of scaffolds 1) Be in a visible place at its access point; 2) Be attached in such a way as to prevent accidental removal, and 3) Show the date and name of the person who inspected the scaffold.

10.1 During the installation of suspended scaffolds, the following shall be complied with: a) Install and assemble the scaffold using the procedure drawn up for that purpose, following the manufacturer's instructions, and only by personnel trained and authorised by the employer for this purpose; b) Install the counterweights specific to each case, where suspension beams are used (see Figure 7). The determination of the counterweight mass shall take into account a minimum safety factor of 4, relative to the sum of the rated capacity of all the winches on the suspended scaffold, using Equation 1: Equation 1 Where: W Is the minimum counterweight to be used to balance the system, with a safety factor of 4; B Is the distance from the point of application of the maximum load to the point of support; C Is the maximum load capacity of the scaffold established by the manufacturer, and A Is the distance from the point of application of the counterweight (W) to the point of support (fulcrum). Figure 7 Counterweights on suspended scaffolds c) Use counterweights made of solid units, not of granular or liquid materials; d) Prevent the location and anchor points of the suspended scaffold from constituting a risk factor; e) Install the cradle or platform of the suspended scaffold at ground level or from the suspension site (see Figure 8). In the case of bridges and places where ground level is inaccessible, the suspension supports shall be designed to facilitate installation; Figure 8 Installation of the cradle or platform f) Indicate the load capacity in a visible place on the equipment, in kilograms if it is less than 1 000 kg, or in tonnes if its capacity is equal to or greater than that weight; g) Attach the suspension and safety cables to a suspension support specific to the type and weight of the suspended scaffold, including its maximum load capacity; h) Verify that, along their path, the suspension and safety cables do not come into contact with sharp or hot surfaces or with high-voltage cables; i) Use restraint systems on the suspension cables at every 15 m of height; j) Run the suspension and safety cables down vertically from the suspension support to the winch, without them bending over cornices, parapets or similar features, or resting on structures with unstable equilibrium; k) Have guardrails around the entire perimeter of their platform, at least 90 cm high, with mesh or 2 rails arranged so that there are no gaps of more than 900 cm; l) Have toe-boards around the entire perimeter of their platform, at least 9 cm high, measured from the platform floor to their upper edge. Toe-boards shall not have any opening greater than

2.5 cm, to contain the fall of any material rolling on the platform floor, and m) Verify that portable masts or any of their components weigh less than 36 kg. Where this weight is exceeded, they shall be fitted with a transport trolley or wheels allowing them to be moved and repositioned.

10.2 During the operation of suspended scaffolds, the following shall be complied with: a) Use powered winches for work involving movements at heights greater than 40 m. On chimneys and sites with a high degree of explosion risk, the use of manual winches is permitted regardless of height; b) Operate suspended scaffolds only with workers trained and authorised by the employer, in accordance with the instructions in the manual and the manufacturer's recommendations; c) Verify that, before starting each work shift, the operator: 1) Checks that the suspension support and the scaffold are in safe operating condition, that there are no obstacles interfering with their movement, and that all screws and nuts are correctly tightened, and 2) Tests the winches with their safety devices, both on ascent and descent, at a height of less than 3 m; d) Prohibit safety devices from being disabled, interfered with or disconnected; e) Provide all personnel using the suspended scaffold with at least the following personal protective equipment: 1) A helmet with a chin strap; 2) Non-slip footwear resistant to the materials to which it will be exposed, and 3) A personal fall-arrest system connected to the anchor points on the platform designed for that purpose. Where the scaffold does not have safety cables, the lifeline of the fall-arrest system shall be attached to an anchor point located above and independent of the suspended scaffold; f) Verify that no object protrudes from the platform before starting any movement of the suspended scaffold; g) Place tools, equipment or materials in containers before starting the vertical movement of a suspended scaffold. While the equipment is moving, workers shall not be allowed to hold objects in their hands; h) Supply or remove tools or materials to or from the suspended scaffold in such a way that none of its supports is overloaded and its balance and immobility are not affected; i) Establish and apply safety procedures to prevent tools or materials from swinging during travel; j) Carry out access or egress at safe points, one worker at a time. To perform these actions, the scaffold shall be immobilised by tying or securing it to a fixed structure. Safe points are considered to be those located no more than 50 cm from floor level, from roof level or from the floor level of intermediate levels; k) Raise or lower suspended scaffolds so that their platform does not tilt more than 20% (11 degrees) from the horizontal; l) Stabilise suspended cables that are not under any tension, where their length exceeds 61 m; m) Periodically inspect the travel rails of suspended scaffolds, in accordance with the manufacturer's instructions, to ensure their safety and correct operation; n) Verify that, under no circumstances, is it permitted to: 1) Raise or lower workers using the suspension cables; 2) Exceed the maximum load capacity established by the manufacturer; 3) Exceed the ascent and descent speed of powered suspended scaffolds of 0.3 m/s, in the case of single-speed powered winches, or 0.4 m/s, in the case of scaffolds with multiple speeds; 4) Move the suspension supports while workers are on the suspended scaffolds; 5) Use suspended scaffolds as load hoists or move them horizontally if a worker is on it, unless the operating manual expressly permits this; 6) Accumulate tools or materials on suspended scaffolds in a quantity that poses a risk of overweight, falling, or creating difficulties in carrying out the activity; 7) Work or remain on the suspended scaffold during electrical storms, strong winds or rain, and 8) Use suspended scaffolds with fibre ropes or cables when working with corrosive substances or with open-flame equipment generating sparks or excessive heat; o) Remove tools or materials from the suspended scaffold and position it on the ground at the end of the work shift, except for installations on bridges and similar structures where ground level is inaccessible; p) Put the platform in the "out of service" position, disconnect the switch and the power source or the mechanical means, fitting locks to prevent unauthorised use, when the operator finishes work, and q) Tie or secure the suspended scaffold to the building, structure or installation when it is out of operation, in such a way that its movement does not cause a risk.

10.3 During the maintenance of suspended scaffolds, the following shall be complied with: a) Carry out maintenance work on suspended scaffolds only with workers trained and authorised by the employer; b) Establish and apply an energy isolation procedure, in accordance with NOM-004-STPS-1999, or those replacing it; c) Make any alteration to the suspended scaffold's original design, installation, operation or maintenance that could affect safety in use subject to written endorsement by the manufacturer and authorisation by the employer, in which case workers shall be given the information needed to operate it safely; d) Periodically inspect the winch and safety devices, in accordance with the manufacturer's instructions; e) Provide, in the winch maintenance manual, instructions for replacing the cable when conditions arise that make it unsafe, among others: 1) The presence of twelve randomly broken wires in the same cable; 2) Wear of the individual outer wires by more than one third of the original diameter; 3) Evidence of damage from heat, wear, flame burns or corrosion, and 4) The formation of waves or unbalanced twisting of the cable (see Figure 9); Figure 9 Examples of unsafe cable conditions f) Clean the platform of suspended scaffolds at the end of maintenance, especially where aggressive chemical products have been used, and leave it free of substances such as soapy solutions, oil, grease, paint, mud or others that could make it slippery or create any other risk to workers, and g) Verify that the suspended scaffold is correctly installed and in safe working condition on completion of maintenance.

11.1 The manuals for the operation, inspection and maintenance of the platform shall be held and available, in the Spanish language.

11.2 Elevating work platforms shall have the components indicated below: a) A basket or work platform, built into the equipment, which shall have lateral protection at least 90 cm high. Ropes, cables, chains or any other flexible material shall not be used to replace the basket; b) Safety devices to ensure their levelling, or stabilisers at the worksite, in accordance with the manufacturer's specifications; c) A ground control panel and one in the basket, with devices allowing workers to lower the platform to the ground in an emergency; d) An automatic audible alarm system, to indicate the platform's ascent, descent, travel - forward or reverse movement -, and any other type of movement - elevation and movement of the telescopic arm -; e) An anchorage device, for connecting the personal fall-arrest system - harness, lifeline, energy absorber, among others -, built into the platform basket or arm, and f) A travel-speed limiter, with the arm extended.

11.3 At the start of each working day, a visual inspection and functional test of the elevating work platform shall be carried out to verify the proper operation of the following elements: a) Operating and emergency controls; b) Equipment safety devices; c) Availability of personal fall-protection equipment; d) Pneumatic, hydraulic, electrical and combustion systems, as applicable; e) Warning and control signals; f) Integrity and legibility of decals; g) Physical condition of the stabilisers, extending axles and structure in general, and h) Any other element specified by the manufacturer.

11.4 At the start of each working day, it shall be verified that the elevating work platform is free of: a) Evidence of deteriorated welds or other structural defects; b) Leaks in hydraulic circuits; c) Damage to cables; d) Poor condition of electrical connections; e) Abnormal conditions in wheels, tyres, brakes and batteries, and f) Residues of aggressive chemical products and of substances such as soapy solutions, oil, grease, paint, mud or others that could make the platform surface slippery or create any other risk to workers.

11.5 During the operation of elevating work platforms, the following shall be complied with: a) Inspect the workplace where the platform will be used before each use; b) Verify, before using the platform, that: 1) The means for maintaining stability are used in accordance with the manufacturer's instructions; 2) The maximum load does not exceed the rated capacity determined by the manufacturer, according to the equipment's possible configurations, and 3) Workers working in the basket or work platform use personal fall-protection systems, anchored to the devices provided and installed within the platform itself, as well as for other risks to which they are exposed owing to the nature of the activities to be carried out, or the place where they will be performed; c) Maintain, before and during operation of the platform: 1) A clear view of the path and area to be travelled; 2) A safe distance from obstacles, natural or accidental depressions or subsidence in the ground or surface, ramps and other risk factors, which shall be specified in the work plan, and 3) The minimum distances to overhead obstacles and energised electrical lines, specified in the work plan or work order; d) Limit the travel speed of the platform, taking into account: 1) Surface conditions; 2) Traffic; 3) Visibility; 4) The presence of slopes; 5) The location of personnel, and 6) Other risk factors; e) Prevent the elevating work platform from being moved on ramps with specifications other than those established by the manufacturer; f) Always lower or close the guardrail or access gate to the basket or work platform before operating the equipment; g) Keep the workers occupying elevated platforms inside the basket or work platform while carrying out their tasks; h) Prohibit workers occupying elevated platforms from sitting, standing or climbing on the protective guardrails; i) Check, while the platform is in use, the equipment's operating area, to ensure that: 1) The operating area meets the conditions specified by the manufacturer; 2) The prevailing weather conditions do not require activities to be stopped; 3) Persons present at the site hold the corresponding authorisation, and 4) The work plan contains the analysis of the safety conditions required to carry out the work, with details of the existing risk factors; j) Avoid the following in the operation of platforms: 1) Placing them on fragile or unstable surfaces or objects; 2) Operating them on uneven or unstable ground outside the manufacturer's specifications; 3) Using them as load cranes; 4) Placing or leaning ladders or scaffolds against the platform; 5) Operating them while on trucks, trailers, cars or other vehicles; 6) Using planks, portable ladders or other similar items intended to gain additional height or reach on the platform; 7) Securing the platform or its occupying workers to fixed structures; 8) Adding large signs or other similar large items that could increase the wind load on the platform, and 9) Using them with internal combustion engines indoors, unless they have ventilation to prevent the build-up of fumes and toxic gases; k) Immediately withdraw the platform from service and mark it, when malfunctions are detected, to prevent its use until the required maintenance has been carried out; l) Verify, before lowering or moving the work platform, that there are no persons, equipment or obstacles in adjacent areas; m) Always carry out the ascent, descent and movement manoeuvres of the platform with the assistance and supervision of at least one second worker, to warn the operator of any hazardous condition, among others: 1) The presence of workers or other persons beneath the platform; 2) Approach to obstacles or energised lines, and 3) The presence of stops, openings, depressions or subsidence on the platform's travel surface; n) Park the base of the elevated platform switched off and protected against unauthorised operation when it is out of service, and o) Recharge batteries in a ventilated space, where there is no risk of fire or explosion.

12.1 Portable ladders shall be inspected before each use. Those with defects that could affect their safe use shall be withdrawn from service immediately and marked with the legend "Dangerous. Do not use." or a similar one, before proceeding to their repair, disposal or destruction. Major repairs shall be carried out by trained personnel.

12.2 Portable ladders shall: a) Be stored in places where they are not exposed to the weather in ways that could damage them, such as sun and rain; b) Be kept free of grease or oil on their rungs; c) Be painted with a transparent material that cannot conceal existing defects or damage, where they are made of wood; d) Be positioned so that the horizontal distance from the foot of the ladder to the point of support - on its vertical - is one quarter of the length of the ladder up to that point of support (see Figure 10); Figure 10 Length of the ladder between its foot and the upper support Where: psa upper point of support pe foot of the ladder x horizontal distance e) Extend at least 90 cm above the point of support at the edge of the surface being accessed, when used to climb onto a roof or other similar elevated surface, and f) Be fitted with non-slip feet. The middle and top sections shall not be used as the bottom section, unless they are likewise fitted with non-slip feet. The use of these feet does not replace the safety measures to be taken when positioning, tying or securing a ladder.

12.3 Portable ladders shall be prohibited from: a) Being stored near radiators, stoves, steam pipes, or other places where they are subjected to excessive heat or moisture, where they are made of wood; b) Being subjected to a load exceeding the maximum established by the manufacturer; c) Being placed on boxes, drums or other unstable bases to reach greater heights, or on sloped surfaces, unless fitted with a system specifically designed for this type of surface; d) Being used simultaneously by more than one person, unless specifically designed for that use; e) Being used as platforms, stands or for any other purpose for which they were not designed, and f) Being improvised with elements to gain additional height beyond their own.

12.4 When performing work at height using a portable ladder, the following safety conditions shall be complied with: a) Visually inspect, before use, the area where the ladder will be used, to ensure there are no hazardous conditions; b) Lock, block or keep permanent watch over doors when a portable ladder is positioned in front of them; c) Ascend or descend facing the portable ladder; d) The operative shall remain facing it while the work is carried out, without the worker's centre extending beyond its side rails. Overreaching to reach a point, area or object in a way that endangers stability shall be avoided; e) Prohibit the user from standing above the third rung from the top while working on a portable ladder; f) Use footwear with non-slip soles when performing work on portable ladders; g) Have a second person hold the portable ladder at all times from its lower part with both hands, during ascent or descent at heights greater than 5 m; h) Secure both the lower and upper parts when working on a portable ladder. The surface on which the top end of the ladder rests shall be rigid and have sufficient strength for the load applied, and i) Prohibit the use of metal ladders in places where they could come into contact with energised electrical lines.

13.1 Safety nets shall: a) Extend at least 2.5 m outward from the edge of the working surface and be installed as close as possible below the surface to be protected, but in no case more than 6 m below it; b) Be supplemented with light debris-netting to protect personnel working on lower levels from falling materials and debris; c) Be installed in accordance with the manufacturer's specifications; d) Be fitted with a high-strength perimeter rope and tie ropes at the edges and ends for anchoring to fixed structures, and e) Be subject to inspection and maintenance.

14.1 Workers performing work at height shall undergo medical examinations at least once a year, in accordance with the provisions of the Official Mexican Standards issued in this regard by the Ministry of Health.

14.2 Medical examinations shall meet the following: a) Be recorded in writing or in electronic media, and b) Contain: 1) The worker's name; 2) The worker's medical evaluation, and 3) The doctor's name, signature and professional licence number.

14.3 The most recent examination carried out shall be kept for as long as the worker remains active in performing work at height.

15.1 The emergency response plan shall contain at least the following: a) The person responsible for implementing the plan; b) The procedures for: 1) Raising the alarm, in the event of an emergency; 2) Communicating the emergency, together with the directory of emergency assistance services (rescue, hospitals, among others); 3) Suspending activities; 4) First aid in the event of accidents; 5) Eliminating risks during and after the emergency; 6) The use of rescue systems and equipment, as applicable, and 7) Resuming activities; c) The identification of the evacuation and escape routes from the building or area where the activity at height is performed, particularly where it is performed by personnel unfamiliar with that building or area, as applicable; d) The actions to be implemented in the event of any failure of the system or equipment in use, including the power supply of powered systems; e) The rescue, personal protection or other systems and equipment required to deal with emergencies that may arise in each of the work-at-height activities carried out, and f) The training and instruction of workers regarding the content of the plan.

16.1 Workers performing work at height shall be provided with training, instruction and information according to the type of system or equipment used, the tasks assigned and emergency response.

16.2 The training and instruction of workers working with personal systems for work at height shall consider at least the following: a) The systems or equipment available for performing work at height and for protection against falls from height; b) The composition, characteristics and operation of the system or equipment used; c) Aspects relating to: 1) The selection and installation of safe anchor points and anchorage devices; 2) The correct way to install, position, adjust and use the system or equipment; 3) Correct connections and attachments; 4) The routine inspections required by the system or equipment, their frequency, and the criteria for withdrawing them from service, in accordance with the manufacturer's instructions; 5) The limitations and possible restrictions on the use of the system or equipment; 6) The estimation of the total fall distance, including the deceleration distance of the energy absorber, to prevent collision or impact with a lower level or with any object in the path of a possible fall; 7) The catenary formed in horizontal lifelines, as applicable; 8) How to prevent the pendulum effect, and 9) The methods for using, inspecting, cleaning and storing the system or equipment, among others; d) The conditions of use to be avoided so as not to reduce the strength capacity or general safety of the systems or equipment, such as: 1) Assembling incompatible components from different manufacturers; 2) Alterations or additions not authorised by the manufacturers; 3) Possible localised overstressing of certain components of the system or equipment, where it has not been properly installed; 4) Exposure of ropes to the cutting effect of edges or pointed objects, and 5) Exposure of the system or any of its parts to corrosive substances or other conditions that could degrade the materials, such as heat, fire, solar radiation, among others; e) The correct way to assemble the system with other types of complementary systems or equipment, as applicable. For example, fall-arrest systems with controlled ascent/descent, positioning or rescue systems, among others; f) The conditions under which systems or equipment shall be taken out of service for repair or replacement, by personnel trained and authorised by the employer, in accordance with the manufacturer's requirements; g) The safety measures established in this Standard applicable to the activities to be performed; h) The weather conditions or other unfavourable factors that would require work at height to be interrupted; i) A general description of the effects on the body during the arrest of a fall and the subsequent suspension, with emphasis on the conditions to be avoided to prevent injury or other harm to health; j) The content of the emergency response plan and other actions arising from emergency situations that may occur during the performance of work at height, and k) The theory and practice of techniques and the use of rescue-at-height equipment.

16.3 The training and instruction of workers working on tower- or structure-type scaffolds shall cover at least the following: a) The procedures for assembling and dismantling the scaffold used, where workers carry out or take part in this activity; b) The fundamental aspects of scaffold safety and inspection; c) The scaffold's stability conditions in aspects such as the placement surface, maximum height, levelling and securing; d) The content of the safety measures established in this Standard; e) The content of the manufacturer's manual or instructions, where available; f) The correct use of the personal fall-arrest system; g) The use of personal protective equipment according to the risks of the activity performed; h) The signage to be used to demarcate the work area; i) The restrictions on use due to adverse weather conditions, the proximity of electrical lines and the load capacity of the scaffold; j) The safe way to ascend and descend from the work platform; k) The safe methods for raising or lowering equipment, tools and work materials to or from the scaffold; l) The procedures for moving the scaffold, and m) The content and implementation of the emergency response plan.

16.4 The training and instruction of workers working on suspended scaffolds shall cover at least the following: a) The installation procedures, taking into account the placement of supports and anchorages, assembly of the cradle, placement of suspension ropes or cables, calculation and placement of counterweights, among others; b) The fundamental aspects of suspended scaffold safety and inspection; c) The content of the safety measures established in this Standard; d) The content of the manufacturer's manual or instructions, where available; e) The methods for inspecting the safety condition of the scaffold's suspension cables and ropes; f) The use and testing of the safety devices fitted to the scaffold; g) The use of restraint systems on the suspension cables; h) The general operating procedures for the scaffold; i) The correct use of the personal fall-arrest system; j) The use of personal protective equipment according to the risks of the activity performed; k) The signage to be used to demarcate the work area; l) The restrictions on use due to adverse weather conditions, the proximity of electrical lines and load capacity; m) The safe way to ascend and descend from the work platform; n) The safe methods for raising or lowering equipment, tools and work materials to or from the scaffold; o) The procedures for moving the scaffold, such as in the case of systems using monorails or other elements, and p) The content and implementation of the emergency response plan.

16.5 The training and instruction of workers working on elevating work platforms shall cover at least the following: a) The specific use of the model to be used, at their own workplace or at a place with similar conditions; b) The content of the training programme provided by the manufacturer of the equipment to be used; c) The fundamental aspects of safety, operation, performance and inspection, in line with that equipment and its intended means of use; d) The theoretical and practical assessment of the knowledge and skills acquired by the person being assessed; e) The correct use of the personal fall-arrest system, and f) The content and implementation of the emergency response plan.

16.6 The information provided to workers using portable ladders shall cover at least the following: a) The proper selection of the type of ladder; b) The manufacturer's instructions, where available; c) Their use and care, before use; d) The inspection of the ladder's condition; e) Its proper assembly and disassembly; f) Transport, movement, ascent and descent; g) A full understanding of the safe working conditions and hazardous situations that may arise, such as use on wet or slippery surfaces or in the presence of strong winds, and h) The correct use of the personal fall-arrest system.

17.1 The employer may engage an accredited and approved verification unit, under the Federal Law on Metrology and Standardisation and its Regulations, to verify the degree of compliance with this Standard.

17.2 Verification units assessing conformity with this Standard shall apply the compliance criteria set out in the conformity assessment procedure in Chapter 18 of this Standard.

17.3 Accredited and approved verification units assessing compliance with this Standard shall issue a verification report, which shall contain: a) Employer details: 1) The name, business name or corporate name; 2) The full address, and 3) The name and signature of the legal representative, and b) Verification unit details: 1) The name, business name or corporate name; 2) The registration number issued by the accreditation body; 3) The approval number issued by the Ministry of Labour and Social Welfare; 4) The dates on which accreditation and approval were granted; 5) The verification result; 6) The name and signature of the person responsible for issuing the report; 7) The place and date of signature of the report, and 8) The validity period of the report.

17.4 Verification reports issued by verification units shall be valid for two years.

18.1 This conformity assessment procedure applies both to inspection visits carried out by the labour authority and to verification visits carried out by verification units.

18.2 The current verification report shall be made available to the labour authority when requested.

18.3 The aspects to be verified during the conformity assessment of this Standard shall be carried out, as applicable, by physical verification, document review, records or interviews, as follows:

5.1 Documentary. The employer complies when it presents documentary evidence that it has an analysis of the prevailing conditions in the areas where

5.2 Documentary. The employer complies when: ¾ It presents documentary evidence that it has available the instructions, manuals or procedures for the installation, operation and maintenance of the systems or equipment used in work at height, drawn up in the Spanish language, and ¾ Such instructions, manuals or procedures are prepared on the basis of the manufacturer's instructions.

5.3 and 7.2 Documentary. The employer complies when: ¾ It presents documentary evidence that it provides written authorisation to workers performing work at height using tower- or structure-type scaffolds, suspended scaffolds and elevating work platforms; ¾ It demonstrates that the written authorisations provided to trained workers are granted once it has been verified that the required safety measures have been applied, and

7.3 to 7.12 ¾ It demonstrates compliance with the following general safety measures for the performance of work at height: 3 At the edges of roofs, terraces, viewing platforms, galleries or elevated fixed structures, as well as at openings such as boreholes, shafts, wells and vertical tunnels, fixed barriers or lateral or perimeter protection, or safety nets for collective protection against falls from height, are fitted in accordance with Chapter 13 of this Standard, among other preventive elements, or workers are otherwise provided with personal systems for work at height, in accordance with Chapter 8 of this Standard; 3 The system or equipment is inspected before

5.4 and of 8.1 Physical. The employer complies when:

1.20 m. For this purpose, a full-body harness or safety belt is used, connected by a lifeline to a fixed point or device that limits the worker's proximity to that zone, and 3 The positioning

                                       o    Positioning   systems   are    used
                                            only    to

5.4 and 9 Physical. The employer complies when: ¾ It demonstrates compliance with the following safety conditions for the performance of work at height, using tower- or structure-type scaffolds: 3 The scaffold is installed and assembled using the procedure drawn up for that

5.4 and 10 Physical. The employer complies when: ¾ It demonstrates compliance, during the installation of suspended scaffolds, with the following safety conditions for the performance of work at height: 3 The scaffold is installed and assembled using the procedure drawn up for that purpose, following the manufacturer's instructions, and only by personnel trained and authorised by the employer for this purpose; 3 The counterweights specific to each case are installed, where suspension beams are used. The determination of the counterweight mass takes into account a minimum safety factor of 4, relative to the sum of the rated capacity of all the winches on the suspended scaffold, using Equation 1 of this Standard; 3 Counterweights made of solid units are used, not granular or liquid materials; 3 The location and anchor points of the suspended scaffold are prevented from constituting a risk factor; 3 The cradle or platform of the suspended scaffold is installed at ground level or from the suspension site. In the case of bridges and places where ground level is inaccessible, the suspension supports are designed to facilitate installation; 3 The load capacity is indicated in a visible place on the equipment, in kilograms if it is less than 1 000 kg, or in tonnes if its capacity is equal to or greater than that weight; 3 The suspension and safety cables are attached to a suspension support specific to the type and weight of the suspended scaffold, including its maximum load capacity; 3 It is verified that, along their path, the suspension and safety cables do not

                                    o    To   raise    or   lower           the
                                         workers    using   the  suspension    cables

5.4 and 11 The employer complies when:

                                o    Pneumatic,       hydraulic,
                                     electrical   and     combustion, as

                                     •     The safe distance from          the
                                           obstacles,      depressions      or
                                           subsidence,      natural       or

                                •     Operating    them  while  they
                                      are    on     trucks,

5.4 and 12 Physical. The employer complies when: ¾ It demonstrates that, in the use of portable ladders, the following safety conditions are complied with: 3 Portable ladders are inspected before each use. Those with defects that could affect their safe use are withdrawn from service immediately and marked with the legend "Dangerous. Do not use." or a similar one, and are then repaired, disposed of or destroyed; 3 Major repairs are carried out by trained personnel; 3 Portable ladders: o Are stored in places where they are not exposed to the weather in ways that could damage them, such as sun and rain; o Are kept free of grease or oil on their rungs; o Are painted with a transparent material that cannot conceal existing defects or damage, where they are made of wood; o Are positioned so that the distance

5.4 and 13 Physical. The employer complies when: ¾ It demonstrates that, in the use of safety nets, it

5.5 Physical. The employer complies when it demonstrates that it supervises compliance with the safety measures set out in the instructions, manuals or procedures for the installation, operation and maintenance of the systems or equipment used in work at height, as well as

5.6 and 7.13 The employer complies when:

5.7 and 7.14 Documentary. The employer complies when it presents documentary evidence The result of the inspection that: annual, to the systems or

5.8 and 7.15 Records. The employer complies when it presents documentary evidence that: ¾ It keeps a record of the inspections and of the preventive and corrective maintenance carried out on the systems or equipment used to perform work at height; ¾ The record of inspections and maintenance carried out on the systems or equipment is kept for at least one year, and ¾ It keeps a record of the inspections and maintenance carried out on the systems or equipment, in which at least the following is recorded: 3 The general details of the system or equipment, such as make, model and serial number or other individual identification; 3 The dates of inspections and maintenance actions; 3 The observations resulting from the inspections carried out on the system or equipment;

5.9 and 8.4 Physical. The employer complies when: ¾ It demonstrates that it provides workers performing work at height with at least one personal fall-arrest system, in accordance with paragraph 8.4 of this Standard, as well as with the personal protective equipment referred to in Chapters 7 to 13 of this Standard, or with that required on the basis of the risk factors identified in the analysis of the prevailing conditions of the area, in accordance with the provisions of NOM-017-STPS-2008, or those replacing it; ¾ The use of personal fall-arrest systems is mandatory when performing work at height on: 3 Edges of roofs, terraces, viewing platforms, galleries or elevated fixed structures, as well as at openings such as boreholes, shafts, wells and vertical tunnels, where fixed barriers or lateral or perimeter protection cannot be fitted, or personal restraint systems are not used; 3 Elevated fixed structures where safety nets cannot be fitted; 3 Tower- or structure-type scaffolds, above 3.5 m;

                                 3   Synthetic-fibre ropes and straps require             a
                                     or metal cable are used for the lines of procedure     special.

5.10 and 14 Documentary. The employer complies when: ¾ It presents documentary evidence that it carries out medical examinations, at least once a year, on workers performing work at height, in accordance with the provisions of the Official Mexican Standards issued in this regard by the Ministry of Health; ¾ The medical examinations meet the following: 3 They are recorded in writing or in electronic media, and 3 They contain: o The worker's name; o The worker's medical evaluation, and o The doctor's name, signature and professional licence number, and ¾ It presents documentary evidence that it keeps the most recent examination carried out on the worker for as long as the worker remains active in performing work at height.

5.11 and 15 Documentary. The employer complies when: ¾ It presents documentary evidence that it has an emergency response plan in place, arising from the performance of work at height, and ¾ The emergency response plan contains at least the following: 3 The person responsible for implementing the plan; 3 The procedures for: o Raising the alarm, in the event of an emergency;

5.12 Physical. The employer complies when: ¾ It demonstrates that it has a first-aid kit, and ¾ The first-aid kit contains: 3 The first-aid manual, and 3 The treatment materials needed to deal with possible emergencies, identified according to the risks to which workers are exposed and the activities they perform.

5.13 and 16 Documentary. The employer complies when: It is valid to present the

                                ¾   It presents documentary evidence that it provides certificates            of
                                    training, instruction and information to the      occupational     skills
                                    workers who are involved in the        issued    by   training
                                    performance of work at height;           providers, internal or

5.14 Documentary. The employer complies when it presents documentary evidence that it supervises that contractors comply with the provisions of this Standard, when the employer engages the services of third parties to perform work at height.

18.4 The instructions, manuals and procedures for the systems or equipment used in work at height may be drawn up on the basis of those corresponding to similar systems or equipment, where the manufacturer's instructions for them are not available.

18.5 For the selection of workers to be interviewed to verify compliance with the provisions of this conformity assessment procedure, the sampling criterion contained in Table 2 below shall be applied: Table 2 Random 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

18.6 Documentary evidence or records held at the workplace may be produced in printed form or on magnetic media, and shall be kept for at least one year.

19.1 Enforcement of compliance with this Official Mexican Standard is the responsibility of the Ministry of Labour and Social Welfare.

20.1 NMX-S-058/1-SCFI-2005, Safety - Personal fall-arrest systems - Part 1: Full-body harnesses - Requirements and test methods.

20.2 NMX-S-058/5-SCFI-2005, Safety - Personal fall-arrest systems - Part 5: Connectors with automatic closing and locking devices - Requirements and test methods.

20.3 PEMEX Gas and Basic Petrochemicals. SP-PC-040 Critical Procedures. August, 2008.

20.4 Province of Manitoba, Canada. Workplace Safety & Health Division. Fall Protection Guideline. July, 2008.

20.5 Occupational Safety and Health Administration. Regulations (Standards-29 CFR)-1910.28 Safety requirements for scaffolding.

20.6 Occupational Safety and Health Administration. Regulations (Standards-29 CFR)-1910.66 Powered platforms for building maintenance.

20.7 Occupational Safety and Health Administration. Regulations (Standards-29 CFR)-1915.159 Personal fall arrest systems (PFAS).

20.8 NMX-GR-012-IMNC-2000, Platforms or scaffolds, cages, suspended bosun's chairs, access machines for building maintenance - General specifications.

20.9 NMX-GR-013-IMNC-2000, Platforms or scaffolds, cages, suspended bosun's chairs, access machines for building maintenance - Tests.

20.10 International Window Cleaning Association. ANSI IWCA I-14.1-2001. Window Cleaning Safety.

This Official Mexican Standard does not concord with any International Standard, since no such reference existed at the time it was drafted.

FIRST. This Official Mexican Standard shall enter into force three months after its publication in the Diario Oficial de la Federación. SECOND. During the period referred to in the foregoing article, employers shall comply with Official Mexican Standard NOM-009-STPS-1999, Suspended access equipment - Installation, operation and maintenance - Safety conditions, or shall make the adaptations needed to observe the provisions of this Official Mexican Standard NOM-009-STPS-2011, Safety conditions for work at height. In the latter case, the labour authorities shall, at the request of the employers concerned, provide advice and guidance to help them implement compliance, without the employers becoming liable to penalties for non-compliance with the Standard in force. THIRD. As from the date on which this Standard enters into force, Official Mexican Standard NOM-009-STPS-1999, Suspended access equipment - Installation, operation and maintenance - Safety conditions, published in the Diario Oficial de la Federación of 31 May 2000, shall cease to have effect. Given in Mexico City, Federal District, on the eleventh day of the month of April, two thousand and eleven.- The Secretary of Labour and Social Welfare, Javier Lozano Alarcón.- Signature.

Minimum content of the instructions, manuals or procedures for the installation, operation and maintenance of suspended equipment for work at height The content of this guide is a supplement for the better understanding of this Standard and is not mandatory. I.1 The instructions, manuals or procedures for the installation of suspended equipment for work at height may contain the following information: a) Instructions for the installation of this equipment; b) Use restrictions; c) The total load imposed on the support or suspension beam in the building; d) The requirements for fixing or anchoring the rails; e) Assembly and disassembly instructions; f) Information to prevent the combination of unsuitable components; g) Instructions concerning the power supply; h) Instructions on placing the steel cable on the support or suspension beam; i) Instructions to ensure that the suspension system is positioned directly above the platform, and j) The demarcation and signposting of hazard areas around and below the access system, which shall be larger than the area of that system. I.2 The instructions, manuals or procedures for the operation of suspended equipment for work at height may contain the following information: a) A description of the risks when working at height and the importance of following the instructions; b) The authorisation prior to its operation; c) A detailed description of the equipment, its safety devices and the applications for which the equipment was selected, including prohibitions and incorrect uses; d) The prior inspection of all the equipment and safety devices; e) Restrictions on use due to load capacity, height, rain, electrical storms, wind speed and ambient temperature; f) The space needed for the operation and maintenance of the access system; g) A description of the manual controls; h) The means for stopping and, specifically, the emergency stop button; i) Instructions for cases where faults, damage or any other circumstance arises that could endanger workers' safety, including the instruction to suspend work and notify the employer; j) Instructions on how to operate the descent when there is no electrical power; k) Instructions on the actions the operator shall take when the safety device is triggered; l) The means of communication between the worker on the platform and a person located outside it, where applicable; m) Systems or devices to prevent tilting of the system or work platform, and n) Instructions for keeping a record containing at least the following information: 1) The names of authorised workers; 2) The serial numbers of the winches and of the safety devices, where applicable; 3) The specifications of the suspension cable, and 4) Accidents and incidents that have occurred and the corrective actions applied. I.3 The instructions, manuals or procedures for the maintenance of suspended equipment for work at height may contain the following information: a) Instructions for recording the preventive and/or corrective maintenance carried out on each system; b) Drawings and diagrams of the suspended access equipment; c) Warnings regarding the disassembly of the drum springs, where applicable; d) The criteria to be followed in replacing the cables; e) Instructions for identifying faults, how to remedy them and how to start up the equipment after maintenance, using a format containing three columns relating to: faults, causes and possible remedies; f) Instructions on the types of inspections carried out before use in each work shift, and g) The types of maintenance and their frequency.

First-aid kit The content of this guide is a supplement for the better understanding of this Standard and is not mandatory. This guide is based on the first-aid manual of the Mexican Red Cross. II.1 Types of first-aid kit: The type of first-aid kit shall correspond to the activities to be carried out or to the site where it is located. II.2 Characteristics: The important characteristics of the first-aid kit are as follows: easy to carry; visible and easily accessible; identifiable by a green cross; not excessively heavy; without locks or devices that hinder access to its contents, and with a list of contents. II.3 Care: The following precautions are recommended: a) That it be kept in a cool, dry place; b) That the instruments be kept clean; c) That the bottles be closed and preferably made of plastic, and d) That the material be kept in order. II.4 The material making up the first-aid kit may be classified as follows: a) Dry material; b) Liquid material; c) Instruments, and d) Supplementary material. The quantity of material to be provided shall be subject to the intended use and to the financial means available. All the material mentioned is basic and shall be present in any first-aid kit. II.5 Dry material: Dry material is that which, owing to its characteristics, shall remain in that state. It comprises the following items: a) Cotton wool balls; b) Gauze pads, 5 x 5 cm; c) Gauze compresses, 10 x 10 cm; d) Adhesive tape; e) Elastic roller bandages, 5 cm x 5 m; f) Elastic roller bandages, 10 cm x 5 m; g) Gauze bandages of the same dimensions as the two preceding items; h) 4-, 6- or 8-ply bandage; i) Tongue depressors; j) Fabric dressings or adhesive bandages, and k) Triangular bandage. II.6 Liquid material: It comprises the following solutions: a) Iodine tincture for skin and mucous membranes; b) Neutral soap, preferably liquid; c) Petroleum jelly; d) Alcohol, and e) Boiled or sterile water. The above solutions should preferably be kept in plastic containers, in regular quantities and each labelled to make their use easier. II.7 Instruments: The instruments may consist of the following: a) Straight scissors and blunt-tip scissors; b) Straight Kelly forceps; c) Non-toothed dissecting forceps; d) Thermometer, and e) Rubber tourniquet. The surgical instruments - such as scissors and forceps - should be packed, either in small cloth wraps or in absorbent paper, and labelled with the name of the instrument they contain. II.8 Supplementary material and equipment: This is material that may or may not form part of the first-aid kit, or which, owing to its use, requires specific material. Some items that may be included are: a) Hand torch; b) Cord; c) Surgical gloves; d) Umbilical cord clamp; e) Stethoscope and sphygmomanometer; f) Splints, made of wood or cardboard; g) Immobilisation equipment for multiple-trauma casualties; h) A blanket; i) Insect repellent; j) Cotton swabs, and k) Pencil and paper. ___________________________