II. Epidemiology
- Occupational Asthma accounts for 15% of new Asthma cases in adults
- Estimated 1.9 million new cases/year (2012)
- (2012) MMWR Morb Mortal Wkly Rep 25;61(20):375-8 [PubMed]
III. Types: Occupational Lung Disease
- Work-Aggravated Asthma
- Preexisting Asthma worsened by workplace exposure
- See Intrinsic Asthma
- Occupational Asthma
- Allergic Occupational Asthma (90% of cases)
- Caused by sensitizers (immune-mediated response)
- High molecular weight sensitizers induce IgE response and are most common
- Irritant-induced Asthma (10% of cases)
- Reactive Airway Dysfunction Syndrome
- Irritants cause direct cell damage and inflammation
- Allergic Occupational Asthma (90% of cases)
- Non-Asthma Occupational Lung Disease
- Occupational COPD (accounts for 15-19% of all COPD cases)
- Associated with exposures to coal dust, silica, cotton dust, and cadmium fumes
- Compounded by concurrent Tobacco use
- Interstitial Lung Disease
- Asbestosis
- Eosinophilic Pneumonia
- Hypersensitivity Pneumonitis or extrinsic allergic alveolitis (bird fancier’s lung, farmer’s lung)
- Silicosis
- Occupational COPD (accounts for 15-19% of all COPD cases)
IV. Risk Factors
V. Findings
- See Asthma
VI. Approach
- Diagnose Asthma
- Determine if Asthma is work related
- Pre-work and post-work Spirometry
- Serial Peak Expiratory Flow log four times daily
- Symptoms improve on days away from work
- Determine type of Occupational Asthma (see above)
- Work-Aggravated Asthma (Preexisting Asthma worsened by workplace exposure)
- Allergic Occupational Asthma
- Irritant-induced Asthma
VII. Management
- Completely avoid causative agent
- However, up to 70% of patients have persistent symptoms for years after exposure cessation
- Treat with standard Asthma Management (e.g. Inhaled Corticosteroids, Bronchodilators)
VIII. Prevention
- Offending irritant or allergen exposure
- Adequate respiratory protection
IX. Resources
- National Institute Occupational Safety Health (NIOSH)
- Occupational Safety and Health (OSHA)
- American Thoracic Society - Occupational Lung Disease