The test

Occupational inhalation testing looks at what happens when you breathe in certain substances at work. 

By watching how your respiratory system responds during the test, we can usually identify the substances that are causing you problems.

In some cases we may need to carry out other tests, such as blood tests and peak flow tests, before making a diagnosis. 

The occupational inhalation test is also known as ‘bronchial provocation testing’ or ‘occupational challenge testing’.

During your test

The test exposes you to specific substances that you have come across in your working environment. We closely monitor how your lungs react to these substances throughout the test.

The test is usually conducted over five days (Monday to Friday). You will need to stay in hospital for most of this time. 

Before the occupational inhalation test, we will use a histamine or methacholine reactivity test to see how responsive or reactive your airways are. 

This test is given through a face mask. During the test, you may experience symptoms such as coughing, wheezing, shortness of breath and chest tightness. The test is generally very safe.

Once the reactivity test is completed, we will carry out an inhalation test.

Each day you will be asked to breathe in a substance, and we will monitor what happens. On some days you might breathe in substances that we suspect may be causing you difficulties. On other days we will use inactive substances.

We will not tell you which substances you have inhaled until we have finished all of our tests. This is to make sure that each substance is tested fairly. 

After the tests are finished, we will explain and give you a full written copy of the results.

Measuring lung function

A spirometer is used to monitor your lung function. We will ask you to blow into this machine every hour throughout the day until you go to bed.

You will need to bring a watch and pen, or a phone to record the times and readings of your blows. The team will then analyse these readings to get the results of your inhalation test.

Risks and side effects

The chance of a serious reaction to the inhalation test is very low. 

Side effects may include a mild asthmatic reaction, and symptoms such as coughing, wheezing, shortness of breath and chest tightness. The symptoms may be similar to those you may experience at work. 

If needed, we may give you medicine (such as salbutamol) which works by relaxing the muscles of the airways into the lungs, making it easier to breathe.

Any potential risk of an adverse allergic reaction is monitored at all times. We have measures in place to make sure any risk is as low as possible. 

Occupational lung disease covers a broad group of conditions caused by the inhalation of dusts, chemicals, or proteins.

Your hospital stay

If you are coming to the hospital for occupational inhalation testing, you will usually need to stay at Royal Brompton Hospital for up to a week while we carry out the tests. Your tests will take place in the same building.

You will have spare time during your stay, so it's a good idea to bring things to do and read. You can also bring your mobile phone or tablet. Please bring headphones if you would like to listen or watch things on your mobile device. You can use our free WiFi service to get online.

Please do not drink caffeinated drinks (tea, coffee, cola or hot chocolate) during your stay as these can affect the results.

Royal Brompton is a teaching hospital and takes part in the ongoing education of nurses, doctors and other health staff. Students or health professionals may be in the laboratory to learn about occupational inhalation testing. If you do not want to have students present during your tests, please let us know before you arrive on the ward. 

Visit our inpatient information page to find out more about what to expect during your stay. 


Our Occupational Lung Disease service provides occupational inhalation testing at Royal Bromopton Hospital. We can also provide further advice and guidance on the tests. 

Find out more about the Occupational Lung Disease service and how to contact the team.