Definition:

• Occupational asthma (OA) = New-onset asthma (or reactivation of dormant asthma) caused directly by exposures at work.

• It is a subset of work-related asthma (WRA).

  • Work-exacerbated asthma = Pre-existing asthma worsened by work conditions (not caused by them).

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Pathophysiology:

• Specific workplace agents → Airway inflammation, bronchial hyperresponsiveness, variable airflow obstruction.

• Common triggers: allergens (e.g., flour dust, animal proteins) and irritants (e.g., chemicals like isocyanates).

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Public Health Importance:

• OA = Most common work-related respiratory disease.

• Incidence correlates with industrialization and exposure to hazardous substances.

• High-risk industries: detergent manufacturing, healthcare, baking, chemical production.

Types of Occupational Asthma (OA) – Introduction

Two main types of occupational asthma (OA) are classified based on whether a latency period occurs before symptom onset:

• Sensitizer-induced OA: Caused by workplace allergens triggering an immune (often IgE-mediated) response after repeated exposure. Symptoms develop gradually over weeks to years.

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• Irritant-induced OA: Caused by non-immunologic irritation from high-dose exposure to chemicals or fumes, with no latency period. Symptoms appear within hours after exposure.

Understanding the distinction between these two types is crucial for diagnosis, management, and prevention strategies.

Type	Mechanism	Latency Period	Common Agents	Key Features
Sensitizer-induced OA (Allergic)	Immune response...