Wildfires are increasing yearly in number and severity as a part of the evolving climate crisis. These fires are a significant source of air pollution, a common driver of flares in cardiorespiratory disease, including
asthma, which is the most common
chronic disease of childhood. Poorly controlled
asthma leads to significant societal costs through morbidity, mortality, lost school and work time and healthcare utilization. This retrospective cohort study set in Calgary, Canada evaluates the relationship between
asthma exacerbations during wildfire
smoke events and equivalent low-pollution periods in a pediatric
asthma population. Air pollution was based on daily average levels of PM2.5. Wildfire
smoke events were determined by combining information from provincial databases and local monitors. Exposures were assumed using postal codes in the health record at the time of emergency department visits. Provincial claims data identified 27,501
asthma exacerbations in 57,375 children with
asthma between 2010 to 2021. Wildfire
smoke days demonstrated an increase in
asthma exacerbations over the baseline (incidence rate ratio: 1.13; 95% CI: 1.02-1.24); this was not seen with air pollution in general. Increased rates of
asthma exacerbations were also noted yearly in September.
Asthma exacerbations were significantly decreased during periods of
COVID-19 healthcare precautions.