Occupational asthma is caused directly by your workplace because of an allergy to something you've inhaled there over a period of time. It's also known as industrial asthma.

It is different to work-exacerbated or aggravated asthma, which is what happens when you already have asthma but it gets worse when you work in a dusty or fume-filled environment. Or, when the workplace is cold, or the job physically tiring. 

Developing occupational asthma

We don't really know why some people develop an allergy while others don't. Usually, it develops within a couple of years of starting work but sometimes it can take longer. 

During these years, your immune system is builds an allergic response, and 'memory,' to your workplace irritant (otherwise known as an allergen). Once this allergic response has developed, you'll generally experience symptoms of asthma when you come into contact with the allergen. For instance, many people start to sneeze, get a runny nose, or itchy eyes. 

In a lot of cases, people with occupational asthma have naturally created antibodies to the allergen as a result of repeat exposure. These are found in the blood or by skin testing; you may have had a blood or skin test to look for these antibodies. They are not themselves harmful but are a marker of your occupational allergy.

Occupational asthma diagnosis

Your doctor will spend time with you, explaining the diagnosis and the implications for your future health. You may even be advised not to work with the allergen in the long term. Sometimes, however, you may be able to continue your work for a short time, wearing suitable respiratory protection, while you make longer-term plans.

Occupational asthma can be a serious condition leading to severe, chronic asthma if exposure to the allergen that causes it continues unchecked.

The future

The allergy causing your occupational asthma will always be with you, but we have good evidence to show that if you avoid contact with the allergen, most people will recover well.

Sometimes this happens as soon as you are no longer exposed, but recovery can often take up to two years. Sometimes, the longer you have had occupational asthma and have been working with the allergen, the more serious the symptoms are and the longer they take to go away.

In some cases – where the asthma symptoms are quite serious and have been present for some time – they may not go away completely. This is the main reason we advise you to avoid contact with the allergen in the future. Even inhaling tiny amounts may be enough to trigger and prolong your asthma symptoms.

When you have managed to avoid all contact with the allergen, you are
likely to find yourself feeling much better than you have for a long time. You may wish to continue attending our clinic for a while so we can keep an eye on your symptoms and make sure you are recovering.

Affecting work

You will be advised not to come into contact with the allergen in the future, but it may be feasible to carry on working with it in the short term, taking great care to avoid as much exposure as possible and to wear effective respiratory protection.

Your employer has a duty under the Health & Safety at Work Act 1974 to minimise any exposure to hazardous substances in the workplace. They also have a duty to notify the Health and Safety Executive (HSE) of your occupational asthma. They will not use your name. Generally, the HSE will then want to visit your place of work to see if there are ways in which other people can be prevented from developing the condition.

Once you have been diagnosed with occupational asthma, you will need to negotiate with your employer (and, if you have one, your occupational health doctor or nurse) to see if changes can be made to your work/role to make it safer for you or if you can be given an alternative job. 

If your employer cannot find you other, safe work, you may need to find work elsewhere. Some employers offer compensation if this happens, which you would need to discuss with them. If you are looking for a new job, make sure you will not be exposed to the same allergen in the new workplace.

Having occupational asthma should not make you unfit to take a new job – unless of course it involves further exposure to the allergen that caused your problem in the first place. On the whole, people with occupational asthma do well in the long term, although the necessary adjustments can take some time.


With occupational asthma, you may be eligible to make a claim for a small amount of compensation. This is known as Industrial Injuries Disablement Benefit; unfortunately, it is not available to people who are self-employed or in the Armed Forces. 

We can give you a leaflet explaining how to claim Industrial Injuries

Disablement Benefit or further information can be found on the government website.

You may decide to take a legal case against your employer. We cannot advise you about this and you will need to seek advice from a lawyer working in this field of law. If you are in a trade union, it will be able to help you with this.

Find out more about the Occupational Lung Disease service