Occupational asthma is the asthma that is triggered if one is exposed to irritants found in the workplace. The workplace may contain many irritants, like dust, gases and fumes of chemicals. If a person with occupational asthma inhales these irritants, it causes worsening of their asthma symptoms such as coughing, wheezing, chest tightness and difficulty in catching breath. Continuing exposure to these lung irritants may eventually lead to “permanent impairment”, which is “a loss, loss of use, or derangement of any body part, organ system or organ function”.

In order to identify which substances in the workplace are triggering asthma symptoms, a person takes a specific inhalation challenge test. Before taking this test, the person takes a lung function test. This test measures the person’s FEV1 (Forced Expiratory Volume in 1 second). FEV1 is the amount of air that the person expels in the first second after a deep inhalation.

Next, the person breathes in an aerosol. The aerosol is comprised of a tiny amount of a substance (asthmagen) which is suspected to be triggering asthma symptoms. Then the lung function test is again carried out to measure the person’s FEV1 after inhaling the aerosol. If this FEV1 is lower than the previous FEV1 by 15 to 20 per cent, it indicates the person’s asthma symptoms are triggered by exposure to this asthmagen.