Approved code of practice

Appendix 3 - Control of substances that cause occupational asthma

The following is an appendix from the COSHH (control of substances hazardous to health) Approved Code of Practice.  It gives information on the control of substances that cause occupational asthma.



1 - For the purposes of this Appendix:

'Asthma' is characterised by periodic attacks of wheezing, chest tightness or breathlessness resulting from constriction of the airways. A substance is considered to cause occupational asthma if, as a result of exposures in the workplace, it both:

2 - 'Cause' does not, in this context, mean triggering an asthmatic attack in a person who has asthma due to another, unrelated cause (occupational or non-occupational). Occupational asthma may be caused by manufactured chemicals or naturally occurring materials, such as fungal spores. The way in which substances cause asthma is the subject of scientific debate, and this Appendix makes no assumption about the mechanism.

Scope of this Appendix

3 - All substances which cause occupational asthma are within the definition of substances hazardous to health for the purposes of the Control of Substances Hazardous to Health Regulations 2002 (COSHH). Therefore the COSHH Regulations and the main COSHH ACOP, of which this Appendix is part, apply and must be observed by employers.

4 - This Appendix applies to:

5 - This Appendix does not apply to general environmental allergens such as grass pollens and fungal spores unless the work activity generates them or leads to their occurrence at higher concentrations than are normally present in the general environment. Nor does it apply to substances, eg general dust, where exposure may produce asthmatic symptoms in a person with pre-existing asthma but where the substance itself is not a cause of occupational asthma.

6 - This Appendix applies to employers, the self-employed and employees to the extent that duties under the COSHH Regulations may apply to them.

Assessment of the risk to health created by work involving substances hazardous to health (regulation 6)

7 - The risk assessment should:

8 - Assessment of control measures and good working practices for substances which cause asthma should take account of the seriousness of the health effects which could result from a failure of control. Particular attention should be given to identifying and assessing the controls for any short-term exposures which may involve markedly higher concentrations than the long-term average.

9 - Employers are required by the COSHH Regulations to protect the health of employees who have developed occupational asthma even though they may develop symptoms at very low, even undetectable, levels of exposure.

10 - Employers should review assessments regularly as required by regulation 6(3) of COSHH. There should be arrangements for review of the assessment and control measures in the light of experience or if new information becomes available. It is particularly important that there should be an immediate review wherever a case of occupational asthma is confirmed.

11 - The employer should set out procedures for responding to a confirmed new case of asthma, which may be occupationally related. These should include measures to:

Prevention or control of exposure to substances hazardous to health (regulation 7)

12 - Exposure to substances with the potential to cause occupational asthma should be prevented. If that is not reasonably practicable, the objective should be to control exposure so as to prevent employees and others who may be exposed from developing occupational asthma as a result of exposure to those substances. This will involve considering the potential for short-term peaks of exposure as well as longer-term time weighted averages.

13 - If an individual develops occupational asthma to a substance, their exposure must be controlled to prevent triggering further attacks. Suitable levels are likely to be well below any maximum exposure level, where these exist.

Health surveillance (regulation 11)

14 - All employees exposed or liable to be exposed to a substance which may cause occupational asthma should be under suitable health surveillance. The extent and detail of the health surveillance should be related to the degree of risk identified during the COSHH assessment. There should be appropriate consultation with an occupational health professional over the degree of risk and level of surveillance. Health surveillance should include the maintenance of a health record in a suitable form for each exposed individual.

Information, instruction and training for persons who may be exposed to substances hazardous to health (regulation 12)

15 - Employees should be provided with suitable and sufficient information covering in particular:

16 - Employers should also give employees proper training, including induction training before they start the job. Appropriate training should be given in respect of: