Adult Asthma among Workers in Ontario: Results from the Occupational Disease Surveillance System

Rationale: Given that approximately 15% of new onset adult asthma cases originate due to exposures in the workplace, there is a need for systematic and ongoing monitoring of risk among workers. Objectives: To characterize the risk of new onset adult asthma among workers in Ontario. Methods: We utilized 575,379 provincial accepted time-loss workers’ compensation claimants data linked to physician billing data. Workers at-risk of new onset adult asthma were followed from cohort entry date to date of diagnosis, emigration, age 65, death, or end of study period. The case definition required 2+ records for asthma within a 12-month period, within a 3-year time window following cohort entry. Cox regression models were used to generate birth year and sex-adjusted hazard ratios (HR) by occupation, industry and exposures identified using a job exposure matrix (JEM). Sex-stratified risk estimates were also generated. Results: Increased risks were detected among well-recognized groups including bakers (HR 1.60, 95% c...