Satellite Image Shows Canadian Wildfire Smoke Drifting Toward US

The U.S. Midwest is experiencing its first air quality alerts of the season as smoke from wildfires in Western Canada wafts south and east for the second year in a row.

There are 138 active fires across Canada, 40 of which have not been contained, as of 9 a.m. EST Tuesday, according to the Canadian Interagency Forest Fire Centre (CIFFC).

A blaze that NASA has called "one of the most menacing" is burning near the town of Fort Nelson in British Columbia, growing rapidly after it ignited last Friday. Canadian authorities have begun issuing evacuation orders for the areas around Fort Nelson, which has a population of about 3,400.

"Due to the aggressive and extreme fire behavior, we strongly recommend that people avoid travel in and around Fort Nelson," said Cliff Chapman, service director of provincial operations for BC Wildlife Service, in a video update on Facebook.

"The fuels are as dry as we have ever seen. The wind is going to be sustained, and it is going to push the fire toward the community," he added.

There have been 986 fires already this year, burning an area of nearly 600 acres, and the season is just getting started. Wildfire activity typically starts several weeks later into the summer, according to NASA's Earth Observatory.

"Resources within most agencies are adequate to manage their current situation, with light to moderate demand and mobilization of resources occurring through CIFFC," the Canadian organization updated on Monday. Officials in British Columbia have prohibiting open burning until Oct. 31 to protect public safety.

The latest image captured by NASA satellites shows a plume of smoke as it drifts toward parts of the Upper Midwest and Great Lakes regions.

Several states have issued air quality alerts, including in Montana, North Dakota, South Dakota and Minnesota.

The CIFCC has set the national preparedness level to a two, meaning wildfire activity is increasing within one or more jurisdictions and the demand for firefighter and equipment mobilization is light.

Once mobilization demand becomes moderate, high, or in full capacity the level could change to a three, four or five respectively.

The fires come after last year's extremely active wildfire season, which blanketed cities across the U.S. eastern seaboard in smoke last June.

The spread of wildfires is often determined by the types of dry vegetation, moisture levels, wind and heat. The amount of area burned then impacts ecosystems, destroying plant cover and affecting carbon sequestering and storage. Many animals, birds, reptiles and insects are affected as well, as wildfires can lead to a heavy loss of biodiversity. The smoke and ash can also pollute the atmosphere and contaminate water.

For people, breathing in the particulates unleashed by the smoke could lead to headaches, dizziness, eye irritation and other health issues.