Due to the record high air quality indexes, health officials recommend that everyone must wear a tight-fitting mask like N95 and KF94|(@US_Stormwatch)|via EarthCam

As the Canadian wildfire smoke covers large parts of the Eastern US, American air quality has taken a toll causing schools across the East Coast to cancel outdoor activities and airline traffic to slow.

Record high air quality indexes show levels above the threshold of 100, which is considered “unhealthy.” Experts advise millions living in New York, Pennsylvania and Washington, DC to stay indoors and use air purifiers for safety.

On Wednesday evening, Philadelphia issued a “code red” alert. New Jersey and New Haven also faced “very unhealthy” air quality indexes, ranging from 200-300, per AirNow.gov.

The hazy conditions, with reduced visibility and a yellowish tint, have disrupted daily life. The air pollution levels are way beyond normal and are expected to stay as such for the rest of the week.

How to stay safe?
Health officials recommend that everyone must

The start of Canada’s wildfire season has been one of the worst on record with more than 400 blazes reported in Canada—double the seasonal norm.

Wildfires have scorched more than 9 million acres of forest, more than 10 times the area that had burnt by this time last year.