Staff Health and Wellbeing Hub

Asthma in the workplace

Asthma in the workplace

What is asthma?

Symptoms vary from person to person, it is a common condition that affects the lungs caused by swelling (inflammation) of the breathing tubes that carry air in and out of the airways, and so they become temporarily narrow and highly sensitive.

Common triggers;

  • allergies (to house dust mites, animal fur or pollen, feathers)
  • smoke, pollution and cold air
  • exercise
  • infections like colds or flu
  • mould or damp

Identifying and avoiding asthma triggers can help keep symptoms under control.

Work-related asthma

There are two types of work related asthma;

  1. Work-aggravated asthma

This occurs in those who already have asthma, where non-specific agents at work such as dust, cold and dry air irritate the airways.

  1. Occupational asthma

Occupational asthma is preventable and is the result of a reaction that can occur in some people when they are exposed to certain substances known as respiratory sensitisers or asthmagens at work. It can be a serious condition leading to severe long-term asthma if exposure to respiratory sensitisers continues.

Important facts

  • Occupational asthma is the most frequently reported work-related lung disease in the UK. 
  • Reducing airborne exposure levels reduces the incidence of occupational asthma.
  • The best opportunity to reverse or improve occupational asthma occurs with early diagnosis, before lung function is too impaired and with early removal from further exposure to the causative agent.

Symptoms are not immediate because it can take a while to develop sensitivity or immune response and not everyone who is sensitised will develop asthma. However, once the lungs become hypersensitive, further exposure to the substance, even at quite low levels, may trigger an attack. The condition can take weeks, months or years to develop depending on the individual and the substance causing sensitisation.

What are the symptoms of occupational asthma (OA)?

The symptoms can develop right after exposure to a substance but sometimes they appear several hours later. The symptoms of occupational or work-related asthma can improve during weekends or holidays when a person has been away from work. Symptoms to look out for include:

  • Cough
  • Wheeze
  • Tight chest
  • Shortness of breath
  • Conjunctivitis (itchy, red, inflamed eyes)
  • Rhinitis (where the inside of your nose is inflamed with symptoms like a blocked, runny or itchy nose).

Workers should understand the importance of reporting these symptoms if they occur. A clear system is in place to include reporting any symptoms that occur between planned health surveillance assessments by direct contact being made with OHS.

Causes of occupational asthma

There are many different substances that may cause occupational asthma resulting from exposures at work. Occupational asthma is more of a risk where there are high levels of allergens or irritants at work, such as:

Occupational allergens

  • Animal e.g. fur, skin and saliva, as well as dust from animal enclosures (such as in research and veterinary work)
  • Grain and poultry dusts - the most common cause of occupational asthma among agricultural workers
  • Vapours and particles e.g. from surgical techniques in hospitals
  • Latex e.g. used in healthcare settings
  • Flour dust and additives

Occupational irritants

  • Chemicals  e.g. bleach, disinfectants, paint spray
  • Wood dust e.g. produced when machining or sanding
  • Fumes, mists and vapours from electronic, engineering or metal work, from adhesives, and from chlorine in indoor pools.

How is occupational asthma prevented?

Prevent occupational asthma by avoiding exposure to respiratory sensitisers. This can be achieved by following these steps:

  • Be aware of all responsibilities under health and safety laws and regulations.
  • Appoint competent persons to support the purposes of health and safety.
  • Assess exposure to substances which can cause occupational asthma.
  • Implement control programmes using the ‘hierarchy of controls’ – elimination > substitution > enclosure > ventilation > personal protective equipment.
  • Respiratory sensitisers in your workplace should be removed or replaced with a safe alternative. If this is not possible, exposure can be minimised through engineering controls such as enclosures and local exhaust ventilation.

If after carrying out the above steps adequate control is not achieved there will be need to consider use of respiratory protective equipment (RPE). While RPE reduces the numbers of new cases of occupational asthma, it does not completely prevent the disease; it should never be the only or primary means of controlling exposure.

  • Its effectiveness depends on proper supervised use. Even brief removal of RPE can lead to the development of occupational asthma.  Employers should ensure that when RPE is worn, the appropriate type is used and maintained, fit testing is performed and workers know how to wear, remove and replace RPE.
  • Effective risk assessment will determine any requirement to commence health surveillance as a secondary prevention measure to assess and ensure efficiency of control measures (as noted above). Health surveillance should identify early signs or symptoms of asthma, rhinitis and conjunctivitis.  

Health Surveillance

Whilst the most important measure is the primary prevention of occupational asthma by eliminating or reducing exposure to its causes at work, health surveillance as a secondary prevention measure involves the early identification of ill-health caused by work (e.g. detecting signs of asthma in employees at an early stage, ideally before they are aware of any symptoms).

Health surveillance consists of a risk-based scheme of repeated health checks which is achieved over a period of time, respiratory health should ideally be assessed before exposure to provide a baseline. It is important because:

  • Outcome is improved in workers who are included in health surveillance programmes
  • It provides additional information to inform employers if their control measures are effective. It should be noted that occupational health professionals will only provide individual health surveillance information to employers in general terms e.g. stating whether an employee is or is not fit for work.

Criteria for undertaking health surveillance includes when:

  • an individual may be being exposed to a hazardous substance that is linked to an identifiable disease of adverse health effect and
  • there is reasonable chance that the disease or adverse health effect may occur under the conditions of work and
  • there is a suitable and acceptable method of detecting the effect.

The Occupational Health Service (OHS) provides a range of statutorily required Health Surveillance programmes. Where OHS has been informed of an individual having potential exposures to respiratory sensitisers as a result of the work they are doing and a suitable and sufficient COSHH risk assessment indicates that health surveillance is required, OHS will undertake to advise on the frequency and content of a suitable programme to detect early symptom development. OHS determine who can operate the programme, how to manage any people at increased risk, communication of results to employers and the referral arrangements when there are borderline or abnormal test results.

Are employees at increased risk?

  • Someone who has pre-existing occupational asthma caused by previous exposure to a substance.
  • Those who have a history of asthma or hay fever may be more likely to develop symptoms as can smokers However, such personal risk factors are poor predictors of disease and people without such history can also develop occupational asthma.
  • If health surveillance identifies one person as having developed occupational asthma or impaired lung function possibly as a result of work exposures, those others who have similar exposures may be at risk and will be required to undertake enhanced health surveillance. This will require multi-cause investigation or root cause analysis to discover the source of exposure and identify additional controls required.

The likelihood of symptoms improving or disappearing is greatest in employees who have no further exposure to the causative agent.  Therefore, early diagnosis and early avoidance of ongoing exposure, either by substitution of the hazard or where possible by redeployment of the employee offer the best chance of improvement or recovery.

Further information is available on the Occupational Health Service website

Health Surveillance and Safety Critical Medicals | The University of Edinburgh

And in 

HSE General Guidance G402.

Record keeping for health surveillance

The employer must keep a ‘health record’ for each employee, as required by regulation 11 of the COSHH Regulations, (this is not the ‘medical record’ as kept by OHS). Health records must contain information about the worker’s details, where they work, the hazards they have been exposed to and their fitness to continue to be exposed to those hazards. They should not contain confidential medical information. The outcomes from all health surveillance form part only of this health record.

How to access the COSHH Health Passport System including guidance on use is available at;

COSHH Health Passport System (CHPS) | The University of Edinburgh

Collective Feedback

Is part of a requirement under CoSHH to feed results from health surveillance into the risk management system; it is communication of anonymised group data which is provided to work areas involved in the health surveillance programmes to identify patterns or areas of concern, to ensure there is management awareness of these in order for actions to be taken locally e.g. highlighting  potential concerns around compliance, training needs, increased awareness of risk assessments, review of control measures or use of RPE.  

Facefit testing

If you need to wear a well fitted face mask it is essential that you undertake a facefit test before commencing work. The Occupational Hygiene Unit runs the in-house facefit testing programme. Individual tests take approximately 30 minutes including respirator fit training. The test requires some simple exercises (head movements and talking aloud whilst walking on the spot) to be undertaken whilst wearing the respirator.

More information about the facefit testing can be found by following the link below:

Respirator facefit testing

Sources of Guidance and Advice


This information is sourced from Society of Occuaptional Medicine, Asthma UK and the Health and Safety Executive websites. For further information about asthma please see the links below.

Asthma UK

HSE - Asthma

Employers’ Guide to Occupational Asthma | The Society of Occupational Medicine (

COSHH health surveillance - COSHH (

Tips for Managing Asthma at Work |


Further information about the main causes of occupational asthma can be found in Section C of HSE's Asthmagen Compendium.

HSE Asthmagen Compendium