Clean, safe and legal

Summary
• The HSE is embarking on a campaign focusing on the effectiveness of extraction systems.
• Wood dust can be explosive as well as providing fuel to a fire.
• A Workplace Exposure Limit of 5mg/m³ applies to dust from softwood, hardwood and board material.
• Local exhaust ventilation remains the principal method of ensuring dust extraction.

Wood dust is a subject which provokes differing views. Many woodworkers take it for granted and assume that breathing in a bit of dust is all part of the job. However, health, safety and environmental regulators do not view loose dust as an unavoidable consequence of woodworking and enforce a range of legal obligations on companies to this end.

From the health perspective, wood dust can cause a number of significant long-term problems as well as contributing to more immediate incidents. Work by the Health & Safety Executive (HSE) shows that the majority of woodworking companies are failing to comply with their legal requirements in respect of the substance.

As well as risking prosecution, such companies are vulnerable to compensation claims. The vast majority of companies would not be able to defend themselves in such cases as they could not provide documented evidence that that have assessed and managed the risks as far as reasonably practicable. A lack of systematic management on such issues will typically increase the risk perceived by insurers and this will be reflected in premiums.

Furthermore, the HSE is just embarking on a major campaign focusing on the effectiveness of extraction systems as well as revising best practice guidance on the subject.

The problems with dust

There are a number of health issues associated with wood dust:

• asthma: around 150,000 people suffer from occupational asthma and wood dust is the fourth largest cause. It accounts for around 50 new cases each year;
• carcinogenic effect: hardwood dust is a carcinogen linked to nasal cancer;
• fire: wood dust is explosive when mobilised in the correct concentration and it will also provide fuel to a fire;
• slipping hazard: fine dust on smooth floors can lead to a slippery surface;
• MDF: there have been a variety of scares with regard to MDF. A hazard assessment document was prepared by HSE (MDF: hazard assessment document EH75/1). This found that MDF was composed primarily of softwood (85-100%) with up to 15% hardwood. Machining of the substance leads to an atmosphere containing wood dust, free formaldehyde, resin binder and dust particles onto which formaldehyde is adsorbed. A greater amount of fine dust is given off when working MDF, however, the study found no evidence for MDF dust to be treated differently from softwood and hardwood dusts.

As a result of these problems, wood dust is classed as a hazardous substance and is controlled under the Control of Substances Hazardous to Health Regulations 2002 (COSHH). These regulations require companies to reduce the level of personal exposure as far as possible. A written risk assessment is required by companies which handle hazardous substances to show that they have identified the hazard posed by dust, the suitability of current controls and methods to make further improvements.

A Workplace Exposure Limit (WEL) of 5mg/m³ applies to dust from softwood, hardwood and board material. This is the level which cannot be exceeded and which companies must keep as far below as possible. It is impossible to accurately assess the level of exposure just by looking, so companies should measure personal dust exposure levels using small dust-collecting filter pumps fitted to individuals for a specified length of time.

However, surveillance by the HSE (HSE (2000 Wood dust survey 1999-2000: www.hse.gov.uk/fod/wd9900.pdf) shows that many companies fail to meet these requirements. A survey in 1999 produced 386 samples from 47 companies. Of these readings 27.2% were above the limit, only 34% of sites had a written COSHH risk assessment and only 21% had conducted a local exhaust ventilation test in the past 14 months.

Control measures

In order to reduce the level of exposure, COSHH promotes a hierarchy of control measures – eliminate, enclosure and extraction.

It is always preferable to eliminate the hazard at source. Therefore, consideration should be given to the potential to remove unnecessary woodworking tasks or to automate them. This is often impractical, so control might be achieved through enclosure, for example machines such as four-cutters can be enclosed to control dust and concentrate the local exhaust ventilation (LEV).

The use of extraction in the form of LEV remains the principal method of ensuring that dust is removed from the working area before it reaches workers. Such systems need regular servicing and maintenance to remain effective, hence the requirement for LEV systems to be tested at least every 14 months. This may seem a strange time-scale, but the logic is that a task performed at this frequency will progress through the year – for example, January 2007 then March 2008. Thus, testing will occur at times of the year when production and climatic conditions may vary.

HSE campaigns

A new HSE campaign is getting under way to focus on LEV systems. Inspectors will be visiting a wide range of premises to ensure that LEV testing has been conducted and that actions have been taken on the basis of the report recommendations. This follows a tendency of companies to install extraction plant and think that they are protected thereafter. The idea of testing is to highlight problems associated with blocked or split pipework, inappropriate extraction hoods, or hoods which are not being used properly, as well as the addition of too many new machines to an existing system.

In addition, the HSE has been having a campaign on asthma, with wood dust being one of the target areas. The HSE now suggests that, as a minimum, companies should have a questionnaire regarding asthma which is used both pre-employment and

during employment to give early warning of asthma. The questionnaires and guidance is available at www.hse.gov.uk/woodworking/dust.htm.

Once wood dust has been extracted out of the workplace, there are a series of environmental controls which may apply. Under the Environmental Protection Act (EPA) 1990, a permit is required under the “manufacture of timber and wood based products” (PG6/2) guidance note, for any sites processing more than 1,000m³ timber or purely sawing more than 10,000m³. The permit is largely focused on ensuring that dust is kept in a contained manner so that it does not impact on neighbours.

In reality, PG6/2 is unnecessary as it simply duplicates other environmental controls. For example, Part III of the EPA gives powers to local authorities regarding the control of neighbourhood nuisance. Part II of the EPA and the associated duty of care regarding waste, places a duty upon sites to keep waste secure and contained. Furthermore, the Water Resources Act makes it an offence for loose dust to enter controlled waters via surface water drains.