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Workers Height Safety

Published: 01st Jul 2007


In recent years there has been an increasing requirement for industrial process operators to use equipment and services which comply with the standards of the Environment Agency MCERTS scheme. The benefits to process operators are evident in more reliable and appropriate monitoring data.

Another recent development is the introduction of the Work at Height Regulations which came into force in 2005. These regulations apply to all industries and cover elevated work platforms (including scaffolding and permanent platforms), fragile surfaces (e.g. roofs), and any ladders, gangways and stairways used to get to the elevated workplace. These areas of industry are affected:

  • Monitoring organisations - when carrying out periodic stack-emissions measurements from elevated workplaces
  • Instrument manufacturers and suppliers - when installing, servicing and calibrating Continuous Emission Monitoring Systems (CEMS)
  • Regulators (both Environment Agency and Local Authorities)
  • Process operators - who have responsibility for ensuring the elevated workplace is safe and has been inspected

The work at height regulations

The Regulations apply to:

  • Work in any place (this includes any place above or below ground level) where, if measures required by these regulations were not taken, a person could fall a distance liable to cause personal injury. An employer in relation to work carried out by an employee of his; and by any other person under his control. Self-employed people are also covered

The Regulations require the employer to:

  • Avoid carrying out work at height where reasonably practicable
  • Take appropriate measures to prevent falls. These measures include work systems, instructions and training, and also work equipment. Work equipment includes, working platforms, installations, guard rails, barriers, collective fall arrestment devices (e.g. net or airbag), and personal fall protection systems (e.g. ropes, harnesses, fall arrestors) relevant machinery, tools, appliances, apparatus. Collective measures must be given priority over personal protection measures
  • Ensure the work at height is properly planned, appropriately supervised, and carried out in a way that is safe as is reasonably practicable
  • Ensure competent persons carry out all activities (including organisation, planning, supervision and inspection)

The Regulations also contain specific provisions relating to falling objects and danger areas, inspection of work equipment and inspection of elevated workplaces.

Working on platforms at chimney stacks

The Regulations contain a number of Schedules describing the specific requirements for existing places of work (encompassing some permanent access to ducts), working platforms (includes permanent platforms at stacks), scaffolding, guard rails, ladders, and inspection.

For all working platforms, the requirements focus on the need for the working platform to be of sufficient strength and rigidity, and for the supporting structure to be stable and of sufficient strength and rigidity and resting on a suitable surface. Other conditions cover dimensions of the platform and safety features (e.g. no gaps).

There is a specific regulation requiring the employer to carry out inspections. Working platforms and associated guard rails, barriers, toe-boards, ladders, etc., must be inspected at the following frequencies:

  • After assembly/installation but before use
  • At suitable intervals where there has been exposure to conditions causing deterioration
  • At each time an exceptional circumstance has occurred which is liable to jeopardise its safety
  • Prior to use. Before the elevated workplace is used the employer must check the surface, and every parapet, permanent rail or other such fall protection measure

This regulation requires that the employer’s inspection is recorded and kept until the next inspection. Inspection is stated as meaning “such visual or more rigorous inspection by a competent person as to be appropriate for safety purposes. This includes any testing appropriate for those purposes”. A specific schedule lists the particulars to be included in the report of inspection.


The existing system of labelling scaffolding that has passed an inspection is used almost universally throughout industry. This, together with ample HSE guidance, has led to great improvements in safe working at heights across industry in general. However, there are still problems: in the past the STA issued a Health & Safety Bulletin to members when it was reported to us that a scaffold collapsed because it had not been secured to a suitable permanent structure (e.g. the chimney stack). In addition, the STA has, for some time, voiced its concern about the lack of regulation covering permanent platforms - from which a large proportion of stack-emissions monitoring is carried out. Although Environment Agency Technical Guidance Note M1 states explicitly that inspection of platforms is required, there is much anecdotal evidence that this is not happening at many sites. There appears to be a perception that permanent platforms are inherently safer than scaffold, but this is not the case. There have been several deaths caused by falls from permanent platforms during stack monitoring in the US and the UK. Clearly, a permanent platform is safe only if, firstly, it was designed initially to be fit as a working platform for stack monitoring, and secondly it continues to be fit for this purpose. Common sense would suggest that permanent platforms need to be checked to ascertain if this is so. However strong a steel platform may be, if it is attached to a chimney stack by a few rusty bolts that have never been checked it is not likely to be safe! From 2005, it has been an unambiguous legal requirement for operators to inspect platforms and assure the strength, stability and safety of platforms used for stack monitoring. Workers on such platforms - whether carrying out monitoring, instrument service and calibration, or audits - now ask to see the Work at Height Regulation Report of Inspection before they start work.

Periodic inspections for deterioration

The HSE advises that periodic inspections of platforms for deterioration should be risk-based. A competent person should consider the current condition of the platform and its associated work components, take into account the deterioration-risk factors for the platform in question, and develop an inspection regime that is fit for purpose in dealing with the likely risk of failure leading to a dangerous situation.

In a general health and safety context, the hazard is the working at height and the risk is the likelihood that a worker could fall and its consequence (death or injury). However in the context of this document, we are being more specific and treat as hazards those parts of the platform that could fail and the risk as the likelihood that they will fail and its consequence.

Identify the hazards

EN ISO 14122-2: 2001 states (in Section 4.1.1) that working platform components, fixings, connections, joints, supports and foundations must have sufficient rigidity, stability, resistance to environmental effects and accumulation of water. A competent person should identify what parts of the platform are at risk from deterioration that could lead to falls or even collapse.

Some further specific examples are:

  • Supporting legs, struts, floors, grilles and their associated bolts and welds
  • If the platform is not free-standing/self-supporting, the structure (e.g. stack) that the platform is attached to
  • Ancillary features to prevent falls, such as handrails, ladders and steps - workers have reported incidences of handrails in corrosive environments breaking free completely when leaned upon
  • Lightning conductor strips must also be checked

Decide the level of risk

To some extent, the height at which the stack monitoring work is to be carried out is a risk factor determining the likelihood of death and injury in the event of structural failure (Remember that the Work at Height Regulations apply to work in any place, including a place above or below ground level, where, if measures required by the regulations were not taken, a person could fall a distance liable to cause personal injury. However, special provisions apply to workplaces higher than 2 metres.) The type of surface or objects onto which a person could fall also influences the consequence of a fall. However, the HSE has advised against ranking the risk based on height - in practice, a fall from as little as 2 m can kill and most stack emissions monitoring platforms are at least this height.

We therefore assume monitoring platforms have a high “height risk” associated with them and that the main variable affecting risk is the likelihood that the components of the working platform will fail.

Deterioration risk factors

We need to consider if the platform was designed in the first place to cope with the rigors of stack-emission monitoring. As mentioned above, in many cases this will require a baseline assessment by a competent structural engineer to establish its current integrity and condition. If it doesn’t meet an acceptable benchmark for integrity and condition, (plus any specific requirements given in Environment Agency Technical Guidance Note M1 and supplementary stack-emission monitoring standards such as BS EN 13284 and BS EN 1911) then it falls at the first hurdle and the platform needs to be redesigned.

Assuming for the moment that the platform was fit for purpose when new and still is, we now have to consider the extent to which its structural integrity is likely to be affected in the future by risk factors. These may include:

  • Stress and metal fatigue due to physical forces
  • Vibration - as well as causing metal to fatigue, vibration may cause bolts to loosen. This may be from plant/process vibrations and also from the effect of wind on the platform
  • Resistance to environmental effects, such as climate, chemical agents, corrosive gases. There may be “normal” corrosion or there may be accelerated corrosion in especially aggressive atmospheres, whether that is due to the climate (e.g. coastal-marine environment) or sector specific pollutant emissions (e.g. SO2)
  • Likelihood of accumulation of water and condensed vapours; for example. it is known that some designs of handrail are prone to internal condensation of corrosive atmospheres leading to corrosion at their base

Develop a periodic inspection regime that is commensurate with the risk

There are two points to be considered; 1. What the inspection will consist of and 2. How often to carry out periodic inspections for deterioration

The HSE has advised the STA that periodic inspections for deterioration should be risk-based. In other words, where the risk is high the inspection should be more detailed/in more depth and more frequent than when the risk is low.

How to inspect the platform and components

Process operators will then need to carry out appropriate inspections, which may be visual or more rigorous (including testing) by a competent person.

How often to inspect

Most large companies have a general, non-statutory, plant inspection regime. These commonly take place once every 5 years. However, inspection of exposed steelwork at sample locations requires more frequent inspections. Based on the experience of STA member companies operating at installations with stacks, and their experience of problems with corrosion and vibration, the STA’s provisional guidance is that all permanent platforms 2 metres high or greater should, as a minimum, be inspected annually by a competent person. The inspection frequency should be increased where there are more risk factors.

Bringing it all together

The flowing matrix brings together the risk factors and inspection regimes in a simple format. It is always difficult to give absolute recommendations (and indeed it would not be appropriate to do so) where risk decides the best route. The STA hopes that this guide will act as a catalyst for getting the whole process started, and that more precise guidance can be developed as our understanding and experience of the issues grow.

The example shown in the risk matrix is based on a platform in a normal working environment above a flat surface. The height risk would be greater if the platform was above tools or machinery for example. It would be less if the fall were into water (provided you could swim!).


Permanent Platforms:

What are the inspection requirements? New fixed access platforms require a survey after assembly/installation but before use. For existing platforms that have not been built to a recognised design standard, the platform must also have a base-line survey.The platform should then be subject to interim/periodic surveys at a frequency determined by risk assessment (as specified by a Structural Engineer) and then a further inspection prior to use

Who should carry out the base-line survey? A suitably competent person. (e.g. A Structural Engineer)

Who could carry out the periodic inspections? A suitably competent person. (e.g. A Structural Engineer)

Who could carry out the prior to use inspections? This can be a member of your own Engineering staff who has received suitable and sufficient instruction/training from the Structural Engineer on scope and purpose of the interim and prior-to-use inspections. Details of this instruction/training should be formally documented

Is there any other time that the fixed platform should be inspected? Yes, at each time that an exceptional circumstance has occurred which may affect the safety integrity of the fixed platform, e.g. vehicle impact, shock loading, extreme adverse weather etc

Temporary Access Platforms:

Who can construct a temporary platform (Scaffolds)? Persons who have received suitable and sufficient training in the construction of such platforms can construct temporary access platforms. This will normally be a local scaffold provider unless you have suitably trained staff internally

What inspections are required for temporary platforms? On completion of erection, a competent person should inspect the scaffold and common practice is to “scafftag” the scaffold. It should then be inspected at a frequency of no greater than 7 days with the “scafftag” being re-authorised

Is there any other time that the temporary platform should be inspected? Yes, at each time that an exceptional circumstance has occurred which may affect the safety integrity of the temporary platform, e.g. vehicle impact, shock loading, extreme adverse weather etc

What are the weight specification requirements for the temporary platform? All platforms should meet minimum weight criteria required for sampling (400kg point load in BS EN 13284-1:2002). Temporary scaffolds cannot be constructed to this specification and must, instead, be constructed to a minimum “scafftag” category of “Heavy Duty”

Are there any other requirements for temporary platforms? Yes, temporary platforms must be supported by, a permanent structure

Mobile elevated working platforms (‘cherry-pickers’):

Can MCERTS organisation/personnel use a ‘cherry picker’ to conduct sampling? No. Where cherry pickers may have been used in the past by the industry, risk assessment has identified that these are not fit for purpose and not safe. This is based on the fact that a ‘cherry picker’ cannot achieve the 400kg point load, the basket space is too restrictive for the equipment and, by attaching the probe to the stack emission point, one is effectively attaching the basket to the structure and preventing a quick means of escape in an emergencyIt should be noted that the use of ‘cherry pickers’ is in contravention of MCERTS requirements and accreditation or certification can be withdrawn from companies and/or personnel found to be using ‘cherry pickers’ to carry of stack sampling

Fragile Roof Surfaces:

What are the Process Operator’s duties in relation to fragile surfaces? It is the duty of the process operator to ensure the health and safety of non-employees and provide safe access and egress for their place of work. If the stack penetrates a roof surface and the stack monitoring team is required to transfer across such surfaces, the process operator must carry out a suitable and sufficient assessment of the transfer area and provide adequate control measures to prevent a fall through a fragile surface Refer to STA Guidance Note, WAH002 Working on stacks that penetrate fragile roofs for further information

Published: 01st Jul 2007 in Health and Safety International

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Workers Height Safety
By Dave Curtis