Results

Over the 20-year study period, annual burn area in Canada ranged from approximately 1.2 million hectares (2020) to over 18.5 million hectares (2023). The number of bad air days in Toronto varied from 2 days in low-fire years to 28 days in 2023.

Key Findings

• Average annual burn area: 4.2 million hectares
• Average bad air days per year: 8.3 days
• Years with above-average burn area consistently showed above-average bad air days
• The three worst years for Toronto air quality (2023, 2021, 2017) corresponded to the three largest burn area years

A clear upward trend was observed in both variables over the study period, with the most dramatic increases occurring in the last five years (2019-2023).