Occupational Hygiene

What is Occupational Hygiene?

Occupational hygiene is the science of assessment and control of risks to health from exposure to hazards in the workplace. Occupational Hygienists measure, minimise and eliminate these risks to aid employers and employees.


In Victorian times workers were given nicknames that related to their job and there are a couple of well known sayings that illustrate the risks to health from exposure to hazardous substances:

Mad as a Hatter

The Hatter was the person who made top hats and these were given their lustrous appearance by polishing with a mercury based substance. The hatter, suffered from mercury poisoning and exhibited symptoms such as severe and uncontrollable muscular tremors and twitching limbs, called “hatter’s shakes”; other symptoms included distorted vision and confused speech. Advanced cases developed hallucinations and other psychotic symptoms. To the management and the rest of the workforce these were signs that the hatter was going mad, many Hatters died in their thirties.

Daft as a Brush

The “Brush” was the man whose job was to put the glaze on ceramic tiles prior to firing. The glaze was a mixture of hazardous chemicals that were applied by brush from a bucket. The “Brush” breathed in the chemicals and started to experience co-ordination problems and difficulties with speech. Management thought the Brush was bored and so moved him to other jobs putting someone else in his place. Soon a large proportion of the workforce became affected and showed symptoms of madness.

Thankfully, with improved occupational hygiene standards, the majority of occupational health risks have either been eliminated or brought under control. Standards have improved dramatically over recent years as our understanding of the risks, measurement techniques and control measures have improved.

Workplace Risks

Workplaces continue to expose workers to health hazards, and the risks will always need to be properly understood and managed. Even now, whilst standards have improved, new risks constantly emerge and the range of health risks in the workplace is more varied than ever. From not just chemical hazards, but physical hazards such as noise, radiation, ergonomic, biological and psychological hazards too.

Amongst the most common risks are employee exposure to chemicals and dusts through inhalation and employee exposure to noise.

Exposure to Chemicals and Dust through Inhalation

The Control of Substances Hazardous to Health Regulations (COSHH) introduces Workplace Exposure Limits (WEL’s) for hazardous substances and these are published by the HSE in their EH40 document which is updated annually. The list of WEL’s has legal status under the COSHH Regulations. The WEL values should be compared with the actual exposure levels in the workplace, to see whether exposure to a substance by inhalation is being properly controlled. The actual exposure level is measured using workplace air sampling techniques.

For some particularly hazardous substances, there is a legal requirement for the employer to reduce exposure below the WEL to as low a level as is reasonably practicable. For other substances, adequate control has been achieved if exposure is reduced to a level below the WEL. To comply with COSHH, WEL’s must not be exceeded.

Sometimes it is necessary to install Local Exhaust Ventilation equipment to extract fumes, chemicals and dusts etc. from the workplace to reduce the exposure to hazardous substances to an acceptable level. In this case, the COSHH Regulations state that regular checks should be carried out by the user but a thorough examination and test must be carried out at least every 14 months. In some cases, where particularly hazardous substances are emitted, testing must be more frequent. Records of examinations, tests and repairs should be made and retained for at least 5 years.

Exposure to Noise

The Control of Noise at Work Regulations 2005 state that wherever noise levels are at or above 80 decibels, the Employer must carry out a suitable and sufficient assessment of the risk to his employees. The risk assessment must identify all measures needed to comply with the Regulations such as the provision of hearing protection, factory signs, hearing protection zones, employee training and, where appropriate, the provision of health surveillance including hearing checks. The risk assessment will generally involve the measurement of noise throughout the workplace and for specific operator tasks in order to establish which measures are appropriate at which places.