Wildfire smoke makes air unhealthy from US Midwest to East Coast, blanketing cities

During the summer of 2023, extensive wildfires across Canada, particularly in Quebec and Alberta, caused widespread and severe air quality degradation across large portions of the United States. Driven by specific meteorological conditions, dense plumes of smoke traveled thousands of miles, leading to hazy skies and the smell of burning wood from the Midwest to the East Coast. This unprecedented event resulted in air quality alerts for millions of Americans, with many cities experiencing some of the worst air pollution levels globally.

In early June 2023, cities such as New York City saw air quality index (AQI) readings reach hazardous levels, at times surpassing 350, significantly exceeding national air quality standards and any previous records in over five decades for the U.S. Northeast. Later in the month, the smoke shifted, causing Chicago to register the worst air quality in the world, with an AQI of 228, and impacting other areas like Michigan and Pennsylvania. Health officials advised residents, especially sensitive groups, to remain indoors, keep windows closed, and limit strenuous outdoor activities due to the harmful fine particulate matter (PM2.5) in the smoke.

The 2023 Canadian wildfire season was the most intense on record, burning over 40 million acres, an area roughly the size of Georgia. The combination of intense fires and atmospheric conditions, including a slow-moving low-pressure system off the Northeast coast and a high-pressure system in North Central Canada, facilitated the long-range transport of smoke and pollutants into the U.S. This event underscored the significant cross-border impact of wildfires and the challenges they pose to public health and environmental quality.