| 1. Absence of pre-existing respiratory disorder, asthma symptomatology or a history of asthma in remission and exclusion of conditions that can simulate asthma |
| 2. Onset of asthma after a single exposure or accident. |
| 3. Exposure is to an irritant vapor, gas, fumes or smoke in very high concentrations. |
| 4. Onset of asthma occurs within minutes to hours and always less than 24 hours after the exposure. |
| 5. Finding of a positive methacholine challenge test (<8 mg/ml) following the exposure. |
| 6. Possible airflow obstruction on pulmonary function testing. |
| 7. Another pulmonary disorder to explain the symptoms and findings is excluded |
