Causes and Effects of Occupational Asthma
Occupational asthma is attributable to a particular exposure to irritants or sensitizers in the workplace. Its prevalence is estimated to affect three to six percent of the population.
What causes it?
Sensitizers produce antibodies that make the host (humans) more likely to react with increasing symptoms the more they are exposed. There is usually a latency period. This is the period from the first time of exposure to the development of symptoms. It is quite variable in people and can last for years before being clearly identified. The presentation of symptoms is also subtle, not quite as dramatic as a typical asthma attack. It is consistent with the usual pattern of behavior of the asthmatic, which is to get used to the present symptoms, and decrease their activity level (in response) so that the symptoms are not noticeable. This is not a very desirable pattern since it allows for progression of the disease to more severe stages where treatment is more difficult.
1. Airway remodeling
The challenge is that if the sensitizer is not identified, and the worker is allowed to continuously be exposed, the level of sensitization increases and results in permanent changes in the airways. The changes include narrowing of the inner space, a process known as remodeling. This remodeling is, unfortunately, permanent. There are many additional obstacles, from the employer being reluctant to spend the extra resources necessary to modify the environment, to the employee who is reluctant to lose his job (if the employer doesn’t resolve the issue). It should be noted that it is currently illegal to perform screening spirometry during the hiring process for the sole purpose of excluding asthmatics and preventing exposure.
2. Injury to airway lining
The irritants work in a different way. They do not incite an allergic or immune response, but rather cause direct injury to the inner lining of the airways. The effect is noticed almost immediately, unlike the scenario with sensitizers. Such is the case with chlorine, ammonia, and other noxious fumes. The degree of symptoms depends on the intensity of exposure.
3. Reactive Airway Dysfunction
In extreme cases there is Reactive Airway Dysfunction syndrome or RADS. This usually occurs after exposure to high concentrations of noxious fumes in a short time interval. The damage is such that it turns a person without previous history of asthma, into a chronic asthmatic, even after cessation of exposure.
What can you do?
First of all, be aware that there is a disease process, something that asthmatics notoriously tend to deny. More awareness needs to be developed regarding what is happening at the work site. Then it’s crucial to stop the exposure, especially when it’s creating antibodies in a susceptible individual. Sometimes these antibodies can be identified with a blood test or a skin test. Not all the sensitizers incite measurable antibodies, which obviously creates more confusion in making the diagnosis.
Use peak flow measurements. These are simple devices that one uses by blowing fast and hard into a cylinder, and it measures the fastest initial flow of air. A single measure is not very useful, but repeated measurements with peak flow meters can give important information. These tests look for a clear pattern of worsening in the peak flow measurements during work, compared with the peak flow measurements outside.
Occupational asthma can occur in almost every work environment but the most common exposures in the literature are bakers, western red cedar wood workers, cadmium, platinum, metal plating, and diisocyanates in those working with plastics. You can see quite a variety of opportunities.
Unlike other allergic asthma cases, this is not treatable by desensitization. Once occupational asthma is identified, the individual has to be removed from the offending environment. Not just temporarily until the employee gets better, but permanently. This can be a very harsh reality to accept by some of the involved parties.
Next up: What makes an individual likely to develop asthma? If you’ve never heard of the Hygiene Hypothesis, a fascinating topic among scientists, you will be surprised.