Wildfire, Smoke, and Mental Health in Canada

Abstract
Climate change has increased the frequency of environmental disasters, including wildfires. This study combines information on the prevalence and intensity of wildfires with information about hospitalizations for mental health indications in Canada. We consider three mechanisms for effects on mental health. First, we consider fires that are close enough to pose an immediate threat, including those that prompted evacuations. These fires have large effects on hospitalizations for indications including anxiety and depression. Second, we consider fires that are as much as 2000km away, and distinguish between those that are downwind and those that are upwind. Upwind fires could impact mental health through an inflammatory pathway: Fires create harmful particulates that are carried downwind and may cause systemic health effects, including effects on mental health. Fires burning downwind pose no threat in terms of pollution, but may still be salient and contribute to "climate anxiety." We find that upwind fires have negative impacts on anxiety and substance abuse, while downwind fires outside the immediate vicinity have no effect. This comparison suggests that much of the harmful effect of fires on mental health is through the pollution pathway.