At a glance
Work-related asthma includes occupational asthma and work-exacerbated asthma. Occupational asthma is new onset asthma caused by exposures at work. Work-exacerbated asthma is previously diagnosed asthma that gets worse at work. Clinicians should consider work-related asthma anytime a patient is experiencing new or worsening symptoms.
Pathophysiology
The signs and symptoms of work-related asthma are generally the same as those of non-work-related asthma. Work-related asthma is caused or worsened by exposure to workplace sensitizers, irritants, or physical conditions.
Sensitizers
Sensitizers are agents that initiate an allergic (immunologic) response. There is typically a latency period of at least a few months between first exposure and becoming sensitized. Sensitizers are divided into high-molecular weight and low-molecular weight agents:
- High-molecular-weight agents: (e.g., cereals, coffee beans, enzymes, flour, grain dust, plant proteins, seafood, latex, wood dust) stimulate the production of specific immunoglobulin E (IgE) antibodies. During re-exposure, the agent cross-links specific antibodies on mast cells and activates them to release inflammatory mediators leading to asthma symptoms.
- Low-molecular-weight agents: (e.g., acrylates, anhydrides, diisocyanates, dyes, formaldehyde, glutaraldehyde, metals, persulfates) are incomplete antigens, called haptens, that often combine with a protein to produce a sensitizing agent.
Irritants
- Induce a non-allergic response and include gases, fumes, vapors, and aerosols.
- Non-allergen-induced asthma pathophysiology is less understood.
Physical conditions
- Exposure to cold air and physical exertion.
- Cooling or drying of the airway is thought to lead to bronchoconstriction.
Regardless of the asthma trigger type, the response is characterized by inflammation, edema, bronchoconstriction, and buildup of mucus in the airways. This leads to coughing, wheezing, chest tightness, and shortness of breath.