Isocyanates: Health surveillance in motor vehicle repair




Engineering Sheet No 18

HSE information sheet

Paints containing isocyanates


Two-pack spray paints containing isocyanates are used extensively to paint vehicles. In these paints, isocyanate hardeners or activators added to liquid resin react to produce a polyurethane film.

Vapours, spray mists, dusts and deposits containing isocyanates are highly irritant to the eyes and respiratory tract, they may also cause asthma or exacerbate existing asthmatic symptoms. Symptoms that may result from exposure to isocyanates include sore eyes, running nose, sore throat, coughing, wheezing or tight chest, breathlessness.

The spraying of two-pack paints containing isocyanates is one of the most important causes of occupational asthma in the UK. Some people may become sensitised as a result of working with two-pack spray paints, ie they become allergic to isocyanates. In sensitised people, even minute concentrations of isocyanates can lead to asthma attacks. Asthmatic attacks may occur immediately or may be delayed for up to 12 hours after exposure, so symptoms may occur away from work. Fatal cases have been reported but these are rare.


Adequate control when isocyanate paints are used may be achieved by segregating spraying operations from other activities in a booth or enclosure, from which vapour and spray are ventilated to a safe place in the open air after adequate filtration. People inside the booth should wear adequate respiratory protection. Compressed air line breathing apparatus incorporating a full face mask or visor is normally used. The booth needs to be thoroughly examined and tested by a competent person at least every 14 months to check that enclosure and ventilation are effective. Respiratory protective equipment should also be checked at least every month to ensure it is working properly. Records of such checks and of any repairs required should be kept.

Health surveillance

The primary purpose of health surveillance is to protect the health of individual employees who may have become sensitised to isocyanates. The results of the health surveillance exercise can also be used as one means of monitoring the effectiveness of the control and protection measures in place. Positive results from health surveillance may indicate that excessive exposure has occurred in the workplace and this highlights the need to review the control measures in place.

If people are removed from work with isocyanates soon after they develop the allergy then it is likely that no persistent lung problems will occur. If, however, they continue to work with isocyanates then they may well develop long-term irreversible chest problems. Health surveillance can assist in identifying early signs of asthma and action can therefore be taken to prevent longer-term effects.

Health surveillance is required for those exposed to vapour and spray from isocyanate-containing paints during such activities as mixing, spraying and drying.

It is likely that a risk assessment will suggest that a high level of health surveillance would be appropriate for personnel who are exposed to isocyanates. This could be carried out by an occupational health nurse or medical practitioner who is familiar with the risks of the process and principles of health surveillance. The health surveillance should consist of:

  1. a pre-employment assessment involving the taking of a detailed history and an assessment together with measurement of baseline lung function (peak flow and simple spirometry);
  2. a questionnaire for identifying relevant symptoms to be administered at 6 and 12 weeks after starting work with paints containing isocyanates, and at yearly intervals thereafter, together with lung function measurements at the same intervals;
  3. the reporting of relevant symptoms to a responsible person without undue delay;
  4. for every person undergoing health surveillance the employer should maintain a health record (to be kept for 40 years) containing the following particulars:
    1. surname, forenames, sex, date of birth, permanent address, postcode, national insurance number, date of commencement of present employment and a historical record of jobs involving exposure to substances requiring health surveillance in this employment; and
    2. conclusions of other health surveillance procedures and the date on which and by whom they were carried out. The conclusions should be expressed in terms of the employee's fitness for work and will include conclusions of the medical practitioner, occupational health nurse or other suitably qualified and responsible person, but not confidential clinical data.

People working with isocyanate-containing paints who are under health surveillance should be trained to recognise the symptoms of sensitisation and to report them to a named responsible person. Early action can then be taken to initiate further medical investigation and, if appropriate, make changes to the work process to protect their health.

Recognition of unsuspected cases of occupational asthma

Sickness absence records should be scrutinised from time to time to identify absence due to respiratory disease. Complaints of work-related symptoms among employees or leavers should be investigated. A runny nose or sore eyes which appear to be linked to spraying operations may be the first signs that exposure is too high.

Reporting cases

Employers are required to report to the Health and Safety Executive under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR) any medically confirmed cases of occupational asthma arising from exposure to isocyanates.

Further advice

The Employment Medical Advisory Service (EMAS) is available to provide advice on all aspects of occupational asthma arising from the use of isocyanate-containing paints. Details of providers of health surveillance may be obtained from your local EMAS office, trade associations such as the Retail Motor Industry Federation and the Vehicle Builders and Repairers Association and trade journals such as Body and Bodyshop.

Useful publications from HSE Books

General COSHH ACOP, Carcinogens ACOP and Biological Agents ACOP Control of Substances Hazardous to Health Regulations 1994. Approved Code of Practice L5 ISBN 0 7176 1308 9

Preventing asthma at work L55 ISBN 0 7176 0661 9

Isocyanates: Toxic hazards and precautions EH16 (Revised) ISBN 0 11 883581 5

Medical aspects of occupational asthma MS25 ISBN 0 11 885584 0

Health and safety in motor vehicle repair 1991, HSG67 ISBN 0 11 885671 5

Protecting your health at work INDG62 (Rev 1996) (single copies free; ISBN 0 7176 1169 8 for priced packs)

Respiratory sensitisers and COSHH - An employer's leaflet on preventing occupational asthma INDG95 (single copies free; ISBN 0 7176 0914 6 for priced packs)

Breathe freely - A workers' information card on respiratory sensitisers INDG172 (single copies free; ISBN 0 7176 0771 2 for priced packs)

Everyone's guide to RIDDOR 95 HSE31 (single copies free; ISBN 0 7176 1077 2 for priced packs)

The future availability and accuracy of the publications listed in this information sheet cannot be guaranteed.

HSE priced and free publications are available by mail order from HSE Books, PO Box 1999, Sudbury, Suffolk CO10 6FS. Tel: 01787 881165 Fax: 01787 313995.

HSE priced publications are also available from good booksellers.

For other enquiries ring HSE's InfoLine Tel: 0541 545500, or write to HSE's Information Centre, Broad Lane, Sheffield S3 7HQ.

HSE home page on the World Wide Web:

This leaflet contains notes on good practice which are not compulsory but which you may find helpful in considering what you need to do.

This publication may be freely reproduced, except for advertising, endorsement or sale purposes. The information is current at 10/97. Please acknowledge the source as HSE.

Printed and published by the Health and Safety Executive 10/97 EIS 18

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