<s>[INST] What is Work Related Asthma? [/INST] Work related asthma accounts for about 10% of all adult onset asthma. Asthma related to the workplace can be categorised into 2 distinct subsets:

Work aggravated asthma, and
occupational asthma
Work Aggravated Asthma

Persons with work aggravated asthma usually have a history of pre-existing asthma. This usually has been symptomatic and the person may have been on treatment but sometimes they have not. Some but not all of this latter group may give a history of childhood asthma, that they have “grown out” of. They may tell of recurrent asthmatic episodes that are triggered by cold temperatures, excessive exertion, or exposure to irritant aerosols including dusts, fumes, vapours, and gases. These people may get wheezy or have other symptoms at work. The problem can often be eliminated by improving the work environment or avoiding the irritant.

Occupational Asthma

Occupational asthma is caused as a direct result of workplace exposure. There are 2 forms of occupational asthma:

Irritant Induced Occupational Asthma (previously called Reactive Airway Dysfunction Syndrome or RADS) and
Allergic Occupational Asthma. This is the cause of the vast majority of occupational asthma cases.
Irritant Induced Occupational Asthma usually develops after a single, very high exposure to an irritant chemical.  It is a direct “burn” effect on the airways and is not related to the immune system. Examples of causal agents include ammonia, acids and smoke. The high levels of exposure required are usually the result of accidents or some major failure of controls, often in enclosed spaces. The workers nearly always manifest asthma symptoms within 24 hours of the exposure, that is, there is no latent period.  Symptoms will tend to improve over time and may go away entirely but if symptoms persist beyond 6 months persistent problems are possible. Whether recurrent exposure to lower levels of respiratory irritants leads to irritant induced asthma is currently a matter of debate but the majority of experts believe it does not.

Allergic Occupational Asthma is caused by sensitisation or becoming allergic to a specific chemical agent in the workplace over a period of time. This is the mechanism for the vast majority (>90%) of cases of occupational asthma. The sensitisation process does not occur after one exposure but develops over time (i.e., latency period). Latency periods are variable and can be as short as several weeks or as long as 30 years. If exposure is consistent, the period of greatest risk is the first two years of exposure but the risk does not go away after that but may reduce somewhat. Source: Occupational Asthma. Link: https://www.hsa.ie/eng/workplace_health/occupational_asthma_and_dermatitis/occupational_asthma_frequently_asked_questions/. Field: Lung Disease. Disease: Asthma </s>