Associations between Wildfire Smoke Exposure and Chronic Cardiovascular and Respiratory Conditions in Selected Provinces in Canada: A Retrospective Ecological Study

Wildfire smoke (PM2.5) has been recognized as an environmental risk factor with severe adverse health outcomes. Exposure to PM 2.5 can lead to severe cardiovascular and respiratory health conditions. The study aims to assess and examine the ecological associations between wildfire smoke exposure and the burden of chronic cardiovascular and respiratory conditions in Canada from 2010 to 2023, by integrating health outcome data with wildfire activity and air quality indicators across provinces. The study used a retrospective study design to collect secondary data from the Canadian Chronic Disease Surveillance System (CCDSS) for health outcomes (acute myocardial infarction, asthma, chronic obstructive pulmonary disease (COPD), heart failure, stroke) across the selected provinces, from the Canadian Wildland Fire Information System (CWFIS), for wildfire perimeters and their causes, and from the National Air Pollution Surveillance Program (NAPS), for air quality using PM 2.5 concentration as a proxy for air pollution exposure. The correlation between average PM₂.₅ concentrations and incidence rates was weakly negative (r = –0.106, p = 0.238), and the wide confidence interval (95% CI: –0.6357 to 0.1593). Similarly, the correlation between high-risk air quality days (HRD) and incidence rates was also weak and negative (r = –0.042, p = 0.643), again failing to reach statistical significance. The findings indicate that wildfire smoke exposure, though an important environmental health concern, was not a statistically significant predictor of chronic cardiovascular and respiratory disease incidence across the studied provinces. This does not negate the potential health risks of wildfire smoke.