Washington, D.C., will once again be under a "code red" air quality alert due to wildfire haze as smoke from Canadian fires drifts into mid-Atlantic and Northeast states.

The D.C. area is expected to be under "code red" status for Thursday, with the Air Now Air Quality Index, which reports national forecasts for air quality, urging sensitive groups to avoid long outdoor exposure and move outdoor activities inside. The site warns that the rest of the population should consider moving activities indoors. A code orange alert was issued for Wednesday in D.C., with air quality marked as unhealthy for sensitive groups.

UNIVERSAL BASIC INCOME PAYMENTS: HOW EXPERIMENTS SENDING PEOPLE MONEY HAVE WORKED OUT

Anything above 151 on the Air Quality Index, which monitors the density of five air pollutants, is “code red” and considered unhealthy air quality.

The most recent wave of smoke from the wildfires in Canada comes weeks after D.C. experienced considerable air quality issues earlier this month, with the Metropolitan Washington Council of Governments issuing a "code purple" health advisory, marking the region's first code purple day for fine particle pollution under the current air alert system.

D.C. was among the top 10 major world cities for poor air quality on Wednesday afternoon, trailing behind Chicago, Minneapolis, and Detroit, according to IQAir.

Western New York is expected to experience code red levels on Thursday as well, with Gov. Kathy Hochul (D-NY) warning vulnerable groups to take precautions while outside.

CLICK HERE TO READ MORE FROM THE WASHINGTON EXAMINER

The Environmental Protection Agency recommends residents under weather warning due to haze avoid strenuous activities and limit the time spent outdoors. It also urges workers who must work outside to wear an N95 respirator mask, noting cloth masks are not protective from wildfire smoke.

In June, Canada’s wildfires generated over 100 megatons of carbon, reports from the Copernicus Atmosphere Monitoring Service indicate.