Asthma at work

What is it?

There are two types of work-related asthma: work-aggravated asthma (pre-existing asthma that is aggravated by non-specific agents at worksuch as dust or cold air) and occupational asthma (asthma that is caused by exposure to a substance inhaled in the workplace).

Most cases of occupational asthma are caused by an allergy where the person develops antibodies to a substance after breathing it in over some months or a few years. Less commonly it is caused by a single high concentration exposure to an irritant gas or vapour at work such as chlorine or ammonia. 

What are the main symptoms?

The symptoms of asthma are the same whatever the cause, although a distinguishing feature of early occupational asthma is that symptoms deteriorate when at work and improve regularly when away from work (weekends and holidays). About two-thirds of people with occupational asthma also suffer from rhinitis (sneezing, runny nose) and/or conjunctivitis (itchy red eyes). 

What's the risk?

There are over 3,500 new cases of occupational asthma each year in the UK, where it is now the most frequent occupational lung disease.

The people at greatest risk of developing occupational asthma include: bakers, pastry makers, paint sprayers, nurses, chemical workers, animal handlers, food processing workers, woodworkers, welders, electrical workers, cleaners, hairdressers, and dental and laboratory technicians. 

What causes it?

Several hundred chemicals have been associated with occupational asthma. The most common causes are isocyanates (in twin pack spray paint), flour, grain dust, wood dust and solder fumes. Chemicals that can cause occupational asthma are usually identified on manufacturer's safety data sheets by the use of the risk phrase 'R42' - 'may cause sensitisation by inhalation'. 

How is it prevented?

Health and safety laws and regulations require that employers assess and reduce risks in the workplace and inform employees about risks. The most specific legislation in this case is the Control of Substances Hazardous to Health Regulations or 'COSHH'.

The best ways of preventing exposure are elimination i.e.; removing the substance, substitution with a less hazardous substance, enclosure of the process and ventilation of parts or all of the workplace. Respiratory protective equipment (RPE) or masks do not completely prevent the disease and should not be relied upon as the main or only means of prevention. 

Should I have a check-up at work?

Employers should arrange regular health checks for workers who are at risk of developing occupational asthma. This is because the early identification of health effects offers the best chance of cure or of preventing someone's asthma getting worse.

If the risk assessment shows that the risk is low, then the health check might simply involve filling in a questionnaire enquiring about your breathing and whether you have a runny nose or itchy eyes.

Where there is higher risk, you should be seen by a nurse or technician who will ask you to blow into a spirometer, a machine that measures your lung volume. These health checks should be performed at least every year.  If you work with flour or animals and a few other substances it is possible to perform skin prick tests or take blood samples to identify if you have allergic antibodies to these substances. 

Should I see a doctor?

If you suspect that you have occupational asthma you should see your family doctor, or a doctor or nurse at work if there is one and seek an early referral to a specialist, since making an accurate diagnosis is not straightforward.

As part of the investigation of your asthma, you will be given a peak flow meter and asked to blow into this at least four times a day, ideally every two hours, for three weeks, both at and away from work. This small machine measures how fast you can breathe out. 

What are the main treatments?

The treatment of adult asthma with medicines is the same whatever the cause. The broader management of asthma depends on whether it is non-occupational, work-aggravated or occupational asthma. If work is not the cause then all you are likely to need is adjustment of your medication. If it is work-aggravated asthma then you and your doctor should work with your employer so that you avoid the triggers that make your asthma worse at work or use respiratory protective equipment.

If you are confirmed as having occupational asthma it is important that you avoid further exposure to the cause completely and early in the course of the disease. This is best managed by being relocated to another area of the workplace and/or to another job, ideally within a year of first noticing symptoms. This offers the best chance of recovery. 

How can I help myself?

To prevent occupational asthma it is important that you follow the job safe practices that are intended to protect your health at work and attend for any health checks associated with your job. If you do develop symptoms, make sure that you see a doctor as soon as possible. If you definitely have occupational asthma, you should avoid any further exposure to its cause. 

What's the outlook?

If within a year of symptoms starting you manage to avoid any further exposure to the causative agent, there is a reasonable chance that your asthma may go away or improve significantly. However, If you continue to be exposed to the cause of your asthma at work, the likelihood is that your asthma will deteriorate and become irreversible. 

Who else can help?

Asthma UK
Telephone: 020 7226 2260

Other websites

• British Occupational Health Research Foundation (BOHRF)
• Health & Safety Executive
• Occupational Asthma

Compiled from information in a BOHRF evidence review by Dr Paul Nicholson, a specialist in occupational medicine. Updated by malehealth for 2008.

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