Causative & risk factors
People can get occupational asthma in 2 ways. They either become sensitive to the allergen that they are being exposed to and later they develop an allergic reaction to that same substance. The other group consists of people who are already suffering from asthma and their attacks are triggered by substances occurring in their workplace.
The occupations at highest risk of producing occupational asthma are spray painting, flour mills, carpentry, animal industries, rubber industry, welding and health care workers.
Clinical presentation
All the classical asthma symptoms are seen such as difficulty in breathing, wheezing, constriction in the chest and coughing. Additional symptoms such as coryza, sneezing, lachrymation and itching of the eyes may be present.
These symptoms can occur within minutes of exposure to the allergen (early-onset reaction) or may begin several hours after the exposure (late-onset reaction). A combination of both reactions can also occur.
It will be noted that these symptoms are usually seen only on working days and may vary in frequency and intensity depending upon the level of exposure to the allergen.
Investigations
A thorough history of the symptoms and their time of occurrence helps diagnose occupational asthma.
Pulmonary function tests (Peak flow monitoring, spirometry, nitric oxide test) are performed to check the lung function.
An aerosol challenge test can be performed with a suspected antigen to confirm whether it triggers asthma. Skin prick allergy testing may be done.
Treatment
Exposure to the offending substances must be minimized as far as possible. Protective equipments like masks etc. must be used to prevent exposure. If exposure to the offending agent cannot be minimized at the workplace, switching jobs may be the only option.
Any form of asthma is usually treated with a combination of short-acting medicines to be taken during an acute attack and long-acting medications to be taken regularly. These medications can be given orally or via an inhaler. They work towards reducing inflammation in the airways and dilating them so that the person can breathe normally again. Anti-allergic drugs may be needed in patients with an underlying allergy.
Alternative therapies like acupuncture, homoeopathy and herbal remedies have beneficial effects in reducing the frequency and intensity of asthma attacks.
