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Statement on Air Quality Alerts Caused by Canadian Fire Smoke by Daniel Tong

by Daniel Tong
Figure 1. A river of thick wildfire smoke flowing from Canada into the Mid-Atlantic region, degrading air quality to unhealthy levels, as shown by this National Oceanic and Atmospheric Administration (NOAA) satellite imagery.
Figure 1. A river of thick wildfire smoke flowing from Canada into the Mid-Atlantic region, degrading air quality to unhealthy levels, as shown by this National Oceanic and Atmospheric Administration (NOAA) satellite imagery. Colored dots represent surface fine particle (PM2.5) readings from EPA ground monitors, with red or purple colors showing unhealthy and severely unhealthy air pollution levels.  

Why and where is this happening?
Since Thursday (July 16, 2026), air quality in the greater Washington, DC area has degraded into severely unhealthy levels. Satellite imagery shows a river of thick wildfire smoke flowing from Canada to the Mid-Atlantic region. The Washington, DC area sits right beneath the central pathway of the “smoke river.” As of Friday, ground air monitors report surface fine particle concentration reaching more than 250 micrograms per cubic meter. At this level, air quality is considered very unhealthy to breathe in.  

Due to high temperatures and dry conditions, hundreds of wildfires are currently active in Canada. The smoke causing poor air quality in DC is traced back to the dozens of large wildfires burning in Ontario, north of Lake Superior.   

How long might the wildfires affect activities in our region? 
Wildfire smoke travels thousands of miles. It takes several days for the smoke to reach the DC area from Canada, and likely several days to be cleaned up, as the ash has been well mixed down to the surface.  

However, the weather is coming in to help. With favorite weather conditions, the thick smoke hovering in our area is expected to thin out. The Hazardous Air Quality Ensemble System (HAQES), jointly developed by George Mason University, University of Texas at Arlington, NOAA, NASA, US Navy and Environmental and Climate Change Canada, shows that air quality will remain poor on Saturday, but improve significantly on Sunday.  

So plan your weekend activities accordingly.  

How poor air quality may impact human health and safety 
Light and tiny, wildfire smoke can reach deep into the lungs with each breath. Exposure to high levels of wildfire smoke leads to exacerbation of asthma, heart failure, and premature death. It can also affect the body’s ability to fight virus and bacterial infection.  

What should you do in our area during this period of wildfire smoke pollution? Here are a few tips: 

  1. Reduce outdoor activities. Note the smoke is very small in size, wearing medical masks will not reduce smoke exposure significantly.   
  2. Get indoors, close doors and windows. If you have an air purifier, turn it on; 
  3. If you have to go outside, avoid high intensity movements to reduce air intake. Jogging or running under this air quality is not recommended. Dog walking should not be long, as animals suffer from smoke exposure as well.  
  4. If you are driving, close the windows, turn on air conditioning, and switch to internal circulation.  Wildfire smoke may reduce visibility and blur a driver’s vision, resulting in traffic accidents. So drive carefully. 
Figure 2. Surface fine paricle (PM2.5) concentrations on Saturday (top) and Sunday (bottom) predicted by the Hazardous Air Quality Ensemble System (HAQES), a multi-agency consensus forecasting of wildfire smoke jointly developed by George Mason University, University of Texas at Arlington, NOAA, NASA, US Navy and Environmental and Climate Change Canada (credit: Yunyao Li, UTA/GMU).
Figure 2. Surface fine paricle (PM2.5) concentrations on Saturday (top) and Sunday (bottom) predicted by the Hazardous Air Quality Ensemble System (HAQES), a multi-agency consensus forecasting of wildfire smoke jointly developed by George Mason University, University of Texas at Arlington, NOAA, NASA, US Navy and Environmental and Climate Change Canada (credit: Yunyao Li, UTA/GMU).  

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