Investigating the Seasonal Impacts of Smoke on Fine Particle Pollution in Chicago

Wildfires are an increasing issue around the world due to the changing climate. These fires emit a variety of pollutants, including particulate matter – which can be extremely harmful to human health. This study examined how fine particulate pollution (PM_2.5) in Chicago, Illinois, was impacted by smoke resulting from wildfires and prescribed burning across North America. This issue has not been well studied due to the fact that Chicago and surrounding areas do not typically experience wildfires nor conduct prescribed burns. However, this does not prevent smoke from being transported into the area, thereby impacting air quality and raising health concerns. Studies of PM_2.5 in Chicago often focus on the summer season. This study used the fire and smoke products from the Hazard Mapping System (HMS) developed by the National Weather Service and PM_2.5 data from the Environmental Protection Agency’s Air Quality System (AQS) to compile a data set for the Chicago area. The dataset consists of PM_2.5 concentration and the level of smoke (None, Light, Medium, and Heavy) for each day from 2019 to 2022. We statistically assessed the relationship between PM_2.5 and smoke as well as examined the seasonal fluctuations of PM_2.5. The results suggest that high levels of PM_2.5 in Chicago are often associated with smoke transported into the Chicago region. This study also found that PM_2.5 affects the Chicagoland area consistently throughout the year and should not be considered a seasonal pollutant. Using NASA’s Worldview images and NOAA’s Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) models, we conducted several case studies. This helped us associate elevated concentrations of PM_2.5 with wildfire smoke. More research is needed to differentiate smoke from wildfires and smoke from other sources to determine the extent to which wildfires are affecting air quality in Chicago.