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Mapping air quality from Canada’s wildfire smoke

June 28, 2023  - By

Smoke from the Canadian wildfires continues to pollute the air across the United States, mainly affecting cities in the northeast, including Pittsburgh, Chicago, Cleveland, Detroit and Buffalo.

According to the New York Times, in early June, the level of particulate matter in the air from smoke became so unhealthy that many U.S. cities set records. Visibility decreased in many cities as well, with the smoke creating an orange haze.

Most of the smoke can be attributed to several fires burning across Canada. Many of these fires were caused by lightning; however, with above-average temperatures and dry conditions, wildfires have been breaking out since May.


A storm system off the coast of Nova Scotia forced smoke from the fires southeast into the United States. (Image: NOAA)

Based on data from the Canadian Interagency Forest Fire Centre, there are 480 active fires in Canada: 252 are out of control, 77 are being held in place, and 151 are under control.

The fires are mapped in the image below.


The red dots represent the out-of-control fires, the green dots are fires being held in place, and the yellow dots are fires that are under control. (Image: Screenshot of CIFFC wildfire map)

Understanding air quality importance

The Air Quality Index (AQI) measures the density of five pollutants: ground-level ozone, particulates, carbon monoxide, nitrogen dioxide, and sulfur dioxide. It was originally established by the Environmental Protection Agency to communicate the cleanliness of the air Americans are breathing every day.

The index runs from zero to 500 — the higher the number the more polluted the air is.

Effects of air pollution can range from mild symptoms, such as eye and throat irritation, to serious ones such as heart and respiratory issues. Pollution can cause inflammation of the lung tissue and increase the vulnerability to infections.

During wildfires, fine particles in the soot, ash and dust can fill the air.

The AQI identifies the concentration of particles smaller in diameter than 2.5 μM. When these particles are inhaled, the tiny specks can increase the risk of heart attacks, cancer, and respiratory infections — especially in children and older adults.

Below is an updated map of air quality from the U.S. AQI as of June 28.


The colors on the map range from yellow — which is unhealthy air quality — to purple, meaning the air quality is hazardous. (Image:

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