Occupational asthma: causes, diagnosis and your rights at work

The Health and Safety Executive (HSE) explains that an asthma attack happens when the airways of the lungs become narrowed, causing an obstruction to the flow of air, with symptoms of coughing, wheezing, breathlessness and a tight chest. During an attack the muscle wall of the small airways contracts and their lining becomes swollen and inflamed, and increased secretions can partly block them.

In occupational asthma the trigger is something breathed in at work. Asthma + Lung UK says that if you develop asthma symptoms when you did not have any before, you may have occupational asthma, and that it does not always appear as soon as you are exposed to a substance. It can take a few weeks to many years to develop, which is one reason the link with work can be missed.

The charity separates it from work-aggravated asthma. If you already have asthma and your work makes it worse, that is not occupational asthma. Even then, it notes that the law says your employer must prevent or control your exposure to hazardous substances and arrange reasonable adjustments if work makes your asthma worse.

HSE keeps a list of substances that can cause occupational asthma, which includes enzymes used in baking and detergents, flour dust, latex, isocyanates, some hardwood and softwood dusts, rosin-based solder flux fume, glutaraldehyde disinfectant, laboratory animal excreta, crustacean and fish proteins, and many more. Asthma + Lung UK lists some of the more common causes and the workers at higher risk.

The symptoms are those of asthma generally: coughing, wheezing, breathlessness and chest tightness. What can point to a work cause, according to the questions Asthma + Lung UK says a GP will ask, is the pattern. Did the asthma symptoms start in adult life? Do they get better on days when you are not at work? Do they get worse after work or overnight?

Because of this, keeping a note of when symptoms occur in relation to tasks, shifts and days off is useful before seeing a doctor. See a GP if you notice asthma symptoms; if symptoms become severe or you cannot speak in full sentences, that is an emergency and you should call 999.

Your GP will ask about your symptoms, your current job and jobs you have done in the past. If they think you may have occupational asthma, Asthma + Lung UK says they will refer you to a specialist, where tests confirm the diagnosis.

The charity lists peak flow monitoring, blood tests or skin prick tests to look for allergy to something you are exposed to at work, and sometimes a challenge test, in which you are exposed to the substance or substances that may be causing the symptoms. The peak flow test needs to be done at least four times a day for at least three weeks with a diary, and your doctor may ask you to record what times you do certain tasks or are exposed to certain substances.

Asthma + Lung UK says treatment for occupational asthma is the same as for asthma not related to work, meaning the usual inhalers and review. The key additional step is to stop exposure to the substance that caused it if you can. It says that around 3 in 10 people with occupational asthma who stop being exposed to the harmful substance make a full recovery.

The sources read for this guide do not give prognosis figures for people who continue to be exposed, so ask your specialist what applies to your situation.

Under the Equality Act 2010, Asthma + Lung UK says your employer must make reasonable adjustments if you have occupational asthma, such as replacing the substance with a safe alternative or moving you to a role where you will not be exposed. Depending on the job, adjustments may not always be possible. Your doctor will ask for your consent before contacting your employer.

HSE explains that the Control of Substances Hazardous to Health (COSHH) Regulations require employers to assess the risk of exposure, to consider substituting harmful products with less harmful ones, and to keep controls in good working order, including local exhaust ventilation and protective gloves. All employees exposed or likely to be exposed to an asthmagen should receive suitable health surveillance. The law also requires employers to report cases of occupational asthma under RIDDOR.

If you have occupational asthma you may be entitled to claim Industrial Injuries Disablement Benefit, and Asthma + Lung UK advises applying as soon as possible. For a civil claim for compensation, it says to seek legal advice as soon as possible, because a claim must be submitted within three years of when you first knew you had the problem. Citizens Advice and trade unions can help.

On the NHS, the usual pathway is GP, then referral to a specialist for testing, with adjustments agreed with your employer. NHS care is free at the point of use.

Some employers offer private occupational health services, and some workers consider private respiratory consultations for faster tests. Whichever route you use, ask for your peak flow results and any specialist letters to be shared with your GP, because you may need them to support benefit and compensation applications.