Occupational Asthma

Occupational asthma is an occupational condition defined as:

"a disease characterized by variable airflow limitation and/or airway hyper-responsiveness due to causes and conditions attributable to a particular occupational environment and not stimuli encountered outside the workplace".

Asthma is defined as a respiratory disease caused by narrowing of the air passages. Symptoms include shortness of breath, tightness of the chest, nasal irritation, coughing and wheezing. The first person to use it in reference to a medical condition was Hippocrates, and he believed that tailors, anglers and metalworkers were more likely to be affected by the disease. Although much research has been done since, the inflammatory component of asthma was recognized only in the 1960s.

Today, asthma affects as much as 15% of the Canadian population (and this is true of other developed countries too) and has increased fourfold in the last 20 years. Various reasons can be identified for this increase - Of course better diagnosis and facilities along with a greater awareness regarding the disease have played a major role. But, one cannot deny the part of increased environmental pollution. Researchers have been working on the relation between the environment and human health since long and the air we breathe is the primary cause for lung diseases like asthma, rhinitis, COPDs, etc. that affect us today.

Approximately 10 to 15% of the adults affected by the disease report an aggravation of their symptoms while at work and an improvement when away, which implies that they may be suffering from Occupational Asthma. Thus, when an individual’s Asthma is caused, not aggravated, by workplace materials, it is defined as Occupational Asthma. In the USA, OA is considered the most common occupational lung disease. At present, over 400 workplace substances have been identified as having asthmagenic or allergenic properties. Their existence and magnitude vary from region to region and the type of industry and can be as varied as wood dust (cedar, ebony, etc.), persulfates (Hairsprays), zinc or even seafood like prawns. For example, in France the industries most affected in order of importance are Bakeries and cake-shops, automobile industry and hairdressers, whereas in Canada the principal cause is wood dust, followed by isocyanates.

Hypersensitivity pneumonitis is a related condition, with many occupational examples (e.g. "Farmer's Lung", "Malt Worker's Lung" and "Humidifier Lung" etc.). However, although overlapping in many cases, hypersensitivity pneumonitis may be distinguished from occupational asthma in that it isn't restricted to only occupational exposure, and involves type III hypersensitivity and type IV hypersensitivity rather than type I hypersensitivity of asthma. Unlike asthma, hypersensitivity pneumonitis targets lung alveoli rather than bronchi.