Continental-scale impacts of fire PM2.5 emissions from boreal and tundra fires on air quality and health

Abstract:

Wildfire is a well-known source of air pollution with documented and quantified health outcomes ranging from acute respiratory and cardiovascular distress to impacts on prenatal development. By injecting pollutants high into the troposphere, it is also a source that can affect vast swaths of the population that are far removed from the source of emission. The US Environmental Protection Agency (EPA) reports tremendous (~25-90%) decreases in concentrations of all air pollutants that have been subject to regulation since the 1990s. However, there are noted exceptions in areas that are affected by wildfire. With some of the highest globally observed increase in temperature trends, ecosystems of the High Northern Latitudes (HNL) across Alaska and Canada have experiences an increase in frequency, extent and severity of fire occurrence. Since 2000, the region has experienced several years of extreme fire occurrence strongly contributing to reduction in air quality within the region and at the lower latitudes. In this study, we use satellite observations of fire activity during the fire season (May– September) across Alaska and Canada between 2001 and 2019 to estimate PM2.5 emissions using the Wildland Fire Emissions Information System. These emissions are subsequently distributed using the NOAA’s HYSPLIT atmospheric transport model to quantify daily concentrations of PM2.5 produced by the HNL events across North America as a whole. Our results show that during years of very high fire occurrence, large plumes of PM2.5 are transported far beyond the boundaries of the region reaching tropical areas below the US Mexico border at concentrations equal to or exceeding those considered dangerous for sensitive groups.