Two classes of work-related asthma

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There are two major classes of work-related asthma, sensitiser-induced and irritant-induced asthma.
The classification is based on the different causes and the course of body response to the cause.
There is also work-aggravated asthma. This is where an element in the work environment causes an asthmatic attack in a person who already had asthma and worsens the symptoms.
Exposure to cold air, dusts, mists, vapour and fumes tends to be the major cause of attacks in this group of asthmatics.
Sensitiser-induced asthma occurs when a worker is exposed to an agent in the work environment, which the body becomes sensitised to, causing an allergic reaction.
The time between exposure and the development of asthma varies. It may range from a few weeks to years.
Irritant-induced asthma occurs when a person is exposed to a substantial amount of an irritating mist, dust, vapour or fumes.
The symptoms usually occur soon after exposure. There is usually no latency period.
Symptoms of asthma include wheezing, chest tightness, shortness of breath and coughing, especially at night.
Other symptoms which can occur and which at times precede the above symptoms include a stuffy nose, itchy eyes or nose and sneezing.
The symptoms of work-related asthma are classically worse at work or soon after work.
Symptoms also tend to increase progressively over the course of the working week.
One gets better at weekends or during holidays away from work. This pattern however is lost as the disease progresses.
Agents that can cause work-related asthma occur at almost all workplaces. The table below, which is nowhere near exhaustive, shows some of the common asthma-inducing agents and some of the types of workplaces or industries where they occur.
The risk of developing work-related asthma exists for virtually anyone. However, the risk is high for those with atopy, that is an inherent tendency to have an allergic reaction, for example those with hay fever, and for those who smoke cigarettes.
For a diagnosis of work-related asthma to be made one would have to present to a medical doctor or other health care provider with symptoms that are consistent with asthma and show a relationship with one’s work or workplace.
A work history showing exposure to known triggers of asthma would support the diagnosis of occupational asthma.
There are specific tests, which are used to confirm the presence of asthma. These include lung function tests and skin prick allergen tests.
Treatment of occupational asthma is the same as that of normal asthma. It is treated with oral medication and inhalers.
In the event of serious attacks there may be need for oxygen therapy with hospitalisation.
Once work-related asthma has been diagnosed and treatment initiated, the primary intervention is to reduce or eliminate the worker’s exposure to the offending agent.
This can be achieved through workplace modifications, such as improving local exhaust ventilation, enclosure of specific processes and lastly use of personal protective equipment.
It might be necessary to completely remove the asthmatic worker from the workplace, because even minute amounts of exposure can lead to an attack, especially in the sensitiser-induced type of asthma.
Every case of suspected occupational asthma should be reported to the Occupational Safety and Health department at NSSA for investigation and assistance in management of the case. Reporting can be done through the employer or by the treating doctor.
Every case of work-related asthma should be treated as a sentinel case that is to say if you identify one case look for others, since the person’s workmates are being exposed to the same asthma-inducing agents.
Actively looking for these affected workers through medical surveillance will allow early detection and treatment.  

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