Gemma’s comment:
I worked for many years in a large public building, which was often described as a “sick” building, in part because of its faulty ventilating system. I often noticed breathing problems, especially when water in the radiators leaked, leaving the industrial carpeting on my office floor damp and probably moldy. Although the building was studied several times by environmentalist specialists and always found to be sick, public funds to fix these problems were never made available. Occupational asthma describes asthma that is caused by exposure to a precise, defined substance in the workplace environment.
Although figures vary from country to country and are difficult to pinpoint, it is estimated that 5–15% of newly diagnosed asthma in working adults is due to occupational (or workplace) exposure. Many physicians fail to consider the possibility of occupational asthma in adults with newly identified asthma and can remain unaware of the disease specifics. Symptoms of occupational asthma may be indistinguishable from those of classic asthma. An astute physician will inquire about current and past jobs held by an adult in whom asthma is newly diagnosed. Another clue to the diagnosis can be provided by close observation of any temporal associations between work, leisure time, and respiratory symptoms.
The NAEPP’s Expert Panel Report-3 points out “occupational asthma is suggested by a correlation between asthma symptoms and work, as well as with improvement when away from work for several days.” Serial peak flow measurements during an entire month, for example, while at work as well as on weekends or days off, can be helpful in identifying patterns that might suggest occupational asthma. It is crucial to recognize occupational asthma because the key to successful treatment is prompt removal of the patient from the workplace exposure that is causing the asthma.
If occupational asthma is properly identified in a timely manner, and if the exposure to the offending agent ceases within a certain period of time, then the prognosis is favorable. If exposure continues, however, there is a “point of no return” past which a per-son with occupational asthma may have permanent respiratory symptoms and disability, even if the exposure ceases at a later date.
Occupational asthma is different from work-aggravated asthma. Work-aggravated asthma refers to preexisting asthma that worsens at work. For example, a person with a history of easily controlled asthma in adolescence might develop an increase in asthma symptoms as an adult when working outdoors during cold winter months. Another example of work-aggravated asthma involves asthma that worsens at work because of irritant exposures, such as might be the case for a bartender with asthma working in a restaurant full of cigarette smoke or an indoor parking garage attendant whose asthma flares from inhaling automobile exhaust fumes. True occupational, or work-related, asthma is a potentially serious medical condition with significant socioeconomic repercussions.
The immunologist and allergist Dr. David I. Bernstein’s 1993 characterization of occupation-al asthma has been widely accepted as the standard definition of the disease. The definition states, Occupational asthma is a disease characterized by variable air flow limitation and/or airway hyper-responsiveness due to causes and conditions attributable to a particular occupational environment and not to stimuli encountered outside the workplace. There are two general types of true occupational asthma (OA). Experts have classified the two types as asthma with latency and asthma without latency. The first type of OA is asthma that develops over time, caused by repeated inhalation of sensitizing work exposures to a specific substance, usually a large protein. Examples of sensitizing agents include formaldehyde, mineral dusts, animal proteins, flours, and grains.
More than 250 different workplace substances have been reported to cause occupational asthma. Different manufacturing industries are involved, from baking, to veterinary work, to paint and circuit board production. Interestingly, not all workers in a certain industry and with clear-cut expo-sure actually go on to develop asthma. Studies suggest that atopy and cigarette smoking may predispose some persons to the development of occupational asthma. The second, more unusual type of OA involves the emergence of new asthma after a single, intense, and often dramatic exposure to potent respiratory irritants, such as bleach, chlorine gas, or strong acids, for example.
Chemical spills and workplace accidents are often implicated. The term RADS describes reactive airways dysfunction syndrome, a type of OA without latency that begins abruptly, usually within 24 hours of an intense, inhaled-irritant exposure that persists for longer than 3 months and behaves like typical asthma. Occupational asthma is more than a single entity, as this answer clearly indicates. If OA is suspected, medical evaluation and consultation by an occupational health physician should be considered.