The main investigation for occupational asthma is your peak flow diary. You should do at least 4 peak flow tests spread throughout the day when you are at work and when you get home. The diary is kept for at least 3 consecutive days. It can be repeated when you are away from work on consecutive days to check for differences.
Some people with asthma may be given an Immunoglobulin E (Ig E) blood test which may show sensitivity to large dust particles.
Other lung function tests can be done in specialist hospitals. However, they will not always show a reaction even if you have a sensitivity to a work place irritant.
Sometimes a skin prick test is done for allergic reactions but many of the industrial causes for asthma cannot be tested using the skin prick method.