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Our latest technical questions and answers

June 2022

Hundreds of people contact our health and safety helpline, seeking advice on topics ranging from working at height to hazardous substances, public safety to PPE, risk assessments to regulations.

These queries are answered by our friendly team of experts.

Here are edited versions of some of the latest questions and answers.

Keeping the noise down

Question I’m aware there are set noise levels to protect people’s health, but are there any recommended levels in relation to allowing people to work in an office without being disturbed or distracted?

Answer The only noise levels set out within health and safety legislation are the ones which relate to noise levels that are loud enough to damage hearing, that is 80 and 85 decibels (dB). Read more in the HSE publication, Controlling noise at work and check out IOSH’s top tips to protect people’s hearing at work.

The following articles may help.

“A series of sound pressure level curves has been recommended to describe acceptable noise levels in various indoor settings. The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) suggests that an open-plan office have a noise criterion range of 40-50 that corresponds to 49-58 dBA. Noises above this level can interfere with voice communications and, for some people, even thought processes.” Read more on Curing the noisy office on the Golden Corporation website.

Another article, Too much noise on the Steelcase website, considers how the level of noise for the type of work taking place in offices is an issue.

“In some open-plan offices, noise ranges from 60 to 65 decibels… this can make cognitively demanding work difficult. Recognising this, the German Association of Engineers has set noise standards in their country for various types of work. While 70 decibels is acceptable for simple or mainly transactional office work, 55 decibels is the requirement for what the association terms ‘mainly intellectual work’. They identify this as work characterised by high complexity and demanding creative thinking, decision-making, solving problems and effectively communicating.

“The recommended noise level for intellectual work pertains to participating in discussions and meetings as well as working solo…

“As Dr Wolfgang Babisch explains, the sound level of speech is about 60 decibels if people talk to one another in normal tones without raising their voices at a distance of about one meter. This means any other noise within that same range – someone else talking nearby, for instance – can cause speech interference, so not all the words may be fully heard. Nevertheless, he says, a sentence may be understood because of cortical processing. This, however, is an active process that may cause reaction leading to adverse effects in the longer run of chronic noise exposure.

“In other words, in noisy environments with poor acoustics, workers can as easily get stressed by trying to hear others as by trying not to hear others – a lose/lose proposition.”

Construction site competency concerns

Question I am concerned about the level of supervision on a construction site. The principal contractor is not on site most of the time. They are available via telephone and have asked one of the contractors to undertake duties in their place. Is this allowed?

Answer There are two aspects to this situation. Firstly, as there is nothing within the legislation that requires a principal contractor to have a physical presence on site at all times, they can delegate carrying out of their duties to another party, such as one of the contractors. However, as they will remain legally responsible, they would need to be very confident that the person they appoint can do so correctly.

Secondly, if you believe that the person appointed by the principal contractor is not competent to carry out the duties properly, then you should raise your concerns with the principal contractor. Ask them to explain why they believe that person has sufficient knowledge, experience etc.

If you are unable to reach an agreement regarding the level of competency, raise your concerns with the Health and Safety Executive (HSE) and ask it to investigate.

Reducing exposure to wood dust

Question What is considered an adequate level when reducing breathing in wood dust? The company currently cuts and routers MDF and I want to check the relevant mitigations are in place.

Answer The relevant health and safety legislation is the Control of Substances Hazardous to Health Regulations (COSHH) 2002 (as amended). The HSE publication, COSHH essentials for woodworkers, Advice for managers, says that exposure to wood dust should be reduced to an ‘adequate’ level. However, it goes on to says that the exposure should be reduced to ‘as low a level as reasonably practicable’.

The HSE’s Workplace exposure limits (WEL) contains a WEL for both hardwood and softwood dust. Where hardwood dusts are mixed with other wood dusts, the WEL for hardwood dust shall apply to all the wood dusts present in that mixture.

It states: “Wood dust is a general term covering a wide variety of airborne wood dusts. Timbers have been divided into two different groups, namely hardwoods and softwoods. Hardwoods are timbers from deciduous trees, including trees from both temperate and tropical zones such as beech, ash, oak, mahogany and teak. Softwoods are mainly from coniferous trees such as Scots pine, yew and cedar.

“Dust is generated by the machining and working of wood and wood-containing materials such as chipboard and fibreboard. Operations such as sawing, turning and routing produce relatively coarse dust, while sanding and assembly operations generate fine dust.”

The following information relates to adequate control for exposure by inhalation and WELs, taken from the guidance accompanying regulation 7 of COSHH.

“HSE has established WELs for a number of substances hazardous to health. These are intended to prevent excessive exposure to specified hazardous substances by containing exposure below a set limit. A WEL is the maximum concentration of an airborne substance averaged over a reference period to which employees may be exposed by inhalation.

“WELs should not be considered a hard and fast line between safe and unsafe. The principles of good control practice require the degree to which exposure is reduced below the WEL to be proportionate to the health risk. If employers apply the principles of good practice for the control of substances hazardous to health correctly, exposure should be below any relevant WEL.

“WELs refer to concentrations of hazardous substances in the air that people breathe, averaged over a specified period of time referred to as a time-weighted average (TWA). Two time periods are used: long-term (eight hours) and short-term (15 minutes). These limits cannot be readily adapted to evaluate or control non-occupational exposure.

“Some substances for which WELs have been approved have been assigned short-term exposure limits (STELs) and have a 15-minute reference period. These substances can have acute effects and the purpose of the short-term limit is to protect against the adverse health effect occurring from brief exposures to the substance.”

Read HSE’s general information relating to the control of wood dust and find out more about working with medium density fibreboard (MDF).

Contact the HSE if you’re concerned about your organisation’s control measures.

Stopping slips and trips in the kitchen

Question What is considered suitable safety footwear to wear in an industrial catering department kitchen, where hot liquids and water are frequently used?

Answer The HSE’s Catering Information Sheet No 6 – Preventing slips and trips in kitchens and food service states: “Footwear can be important in preventing slips in the workplace and selecting the right shoe sole can have a big effect on reducing slip injuries. As a minimum, there should be a ‘sensible shoe’ policy in force. If, after all other reasonable steps have been taken to reduce the risks, a significant slip risk remains, then non-slip shoes may need to be provided.

  • Speak to the manufacturer or supplier of the shoes to ensure they are suitable for the environment in your workplace.
  • Different types of footwear can perform differently in different situations. Slip resistance of footwear does not scale with price; some inexpensive shoes can perform very well.
  • Rubber soles offer more slip resistance on wet floors than polyurethane soles. But you should choose footwear after considering the specifics of your environment, the types of contaminants and work being carried out.
  • Sole tread patterns make a difference to the slip resistance; finer cleats are better, though they should not become clogged with any waste or debris on the floor. If they do, that design of sole is unsuitable for your situation, or you need to control the contamination that gets on the floor.
  • If ‘anti-slip’ footwear is needed to properly control slip risks, the employer must provide and pay for it, as it would constitute personal protective equipment.”

Check out the HSE’s Stop slips in kitchens – A good practice guide, read HSE case studies relevant to the hospitality industry and view research reports.

Got a technical question?

The above questions and responses mostly relate to UK law, so please contact the helpline or your own regulatory body for information relevant to your country.

Call the IOSH health and safety helpline on +44 (0)116 257 3199 or send an email.

Got a membership question?

For any queries relating to your IOSH membership, please call +44 (0)116 350 0800 or email our Customer Service Centre.

Read our previous q&a article.

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Ali Barlow
Content Officer +44 (0)116 257 3117
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