Polluted air from the Canadian wildfires returned to the US this week.
There are nearly 900 fires across Canadabut the smoke this week will come from the western part of the country.
« Unfortunately, smoke from the wildfires will begin to drift back into the region to start the new week, » according to the National Weather Service in the Philadelphia area.
Air quality advisories have been issued for multiple areas, including the Midwest, Great Lakes, central Tennessee and North Carolina, as well as the Northeast.
By 5 a.m. New York time on a Monday, several cities were reporting high Air Quality Index readings: 158 in Buffalo, 155 in Chicago, and 142 in Nashville. The index ranges from 0 to 500; the higher the number, the higher the level of air pollution. An AQI of 201 or more is considered very unhealthy.
Unhealthy conditions are forecast for New York state on Monday, according to AirNowa website maintained by the US Environmental Protection Agency, which oversees air quality across the country.
Statewide Air Quality Health Advisories were issued in New York on Monday. The forecast is expected to cause « unhealthy for all » conditions in the area closest to the Canadian border, according to AirNow. Elsewhere in the state, conditions will reach « unhealthy for sensitive groups » status.
« Smoke from the Canadian wildfires will remain in the picture through Tuesday as upper northwest winds off the Canadian prairies continue to direct more smoke into the Lower 48, » the weather service said.
Early last month, the level of particulate matter in the air from smoking became so unhealthy that many US cities set records. It was sometimes dangerous to breathe everywhere from Minnesota and Indiana to the Mid-Atlantic and Southern sections.
Visibility has dropped to startling levels in cities including New York, Toronto and Cincinnati. In some places, the smoke from the fires covered the sky with an orange haze. That smoke could be traced back to the fires burning in Quebec.