Occupational asthma is asthma that is caused by or aggravated by a person’s work. This condition will not be diagnosed unless one thinks of the association between asthma and a person’s work. The causes are very numerous. There may be delay between starting work and the onset of symptoms. It is important to determine if there is any relationship between symptoms and work such as a reduction in symptoms when away from work and the time of day and time of the week these symptoms occur or get better.
If the association between work and the asthma is detected early it may be possible to remove the worker from the environment and the worker may recover fully. If the association is not recognized the condition may progress to an extent that the asthma will become permanent and may continue even after the worker is removed from that environment.
If work is thought to be a factor it is important that the worker continues at work until such time as the condition can be proven. This is best undertaken by a respiratory physician experienced in this field. This is important for future compensation claims.
Apart from removal of the worker from the offending environment the management of the asthma is the same as that for asthma in general, that is to try and return the worker’s lung function to normal with as few exacerbations as possible.
This lung problem results from the development of hyper-sensitivity reaction occurring in the lung tissue of a worker who breathes in a substance the worker has developed an immune response to. The reaction might be manifested initially by fever and a flu-like illness, chest discomfort, breathlessness and coughing. Examination may reveal crepitations over the lung fields. Lung function tests may show evidence of lung restriction. A chest x-ray may show haziness in the lung fields. If the facilities are available it may be possible to detect antibodies in the workers’ blood to the offending substance.
If the condition is not diagnosed and exposures are repeated over time, the immunological reaction will be repeated on exposure. The symptoms and signs may progress; lung function abnormalities will deteriorate; radiological changes will become chronic and the worker may become disabled and resistant to treatment.
Conditions which cause hyper-sensitivity pneumonitis are not common in this country and should be thought of in agricultural work or those exposed to organic material that may be a good growth medium for a variety of micro-organisms.
These are significant diseases and are due to infections in workers from organisms that grow in animals. The most common one is Psittacosis which is caused by an organism that lives in birds. Pet shop workers and vets are among groups that are infected with this disease. Another organism is the Hendra virus that has caused severe pneumonia in horses and has been transmitted to trainers and vets with devastating results.