Effects of Wildfire Smoke Particulate Matter and Extreme Heat on the Risk of Congenital Heart Defects in Canada

Abstract

Background: Wildfire events and temperature anomalies have been increasing in frequency due to climate change. Prenatal exposures to resulting environmental stressors, including wildfire smoke (WFS) PM₂.₅ and extreme heat events (EHEs) may be associated with adverse birth outcomes, specifically congenital heart defects (CHD).

Methods: The study cohort was developed using health administrative data across Canada, excluding the province of Quebec. Environmental exposures of PM₂.₅ (all-source, WFS, and non-WFS) and ambient temperatures were assigned to each mother-infant pair based on the maternal residential history.

Results: No significant association between WFS PM₂.₅ and CHD was observed. Similarly, no consistent association was identified for EHEs, and no significant additive interaction between WFS events and EHEs was observed.

Conclusion: Overall, no clear evidence of association between WFS PM₂.₅ and EHEs on CHD risk was observed. Further research on the implications of wildfires on the relationship between environmental factors and adverse birth outcomes is warranted.