Orange air quality warning persists across GTA, with temporary relief expected in afternoon

Orange air quality warning persists across GTA, with temporary relief expected in afternoon

After some relief in the afternoon, heavy smoke is expected to come back Friday night, weekend

Despite improvements overnight with the smoke, an orange-level air quality warning by Environment Canada remains in place Friday across the Greater Toronto Area.

Drifting smoke from forest fires in northwestern Ontario are still resulting in "very poor air quality" and reduce visibility Friday morning, said the national weather agency's warning update at 6 a.m.

While "temporary" relief is expected in the afternoon, Environment Canada said heavy smoke will return Friday night and into the weekend.

"During heavy smoke conditions, everyone’s health is at risk regardless of their age or health status," it said, adding people should reschedule or cancel any outdoor activities.

Concentrations of fine particulate matter, or PM 2.5, in the atmosphere have lowered compared to Thursday, according to the province. PM 2.5 are airborne particles that are less than 2.5 micrometres in diameter, smaller than a strand of human hair, and can travel deep into your lungs.

As of 6 a.m. Friday, Toronto has about 71 to 176 micrograms/cubic metre (μg/m³) of PM 2.5 in the air. That's an improvement compared to the nearly 300 μg/m³ measured Thursday morning.

Concentrations of the pollutant are higher in Brampton at 218 μg/m³ and Mississauga at 206 μg/m³, but are lower at 40 μg/m³ in Oshawa.

The province's air quality health index as of 6 a.m. Friday is at 10+, or very high risk, for Brampton, Mississauga and most of Toronto. Meanwhile, Toronto East has come down to 8, or high risk, and Oshawa to 4, or moderate risk.

Toronto air quality may 'temporarily improve' Friday, but conditions could persist into weekend

Toronto the orange: Wildfire smoke leaves city under dirty sky with no relief likely until Friday

Environment Canada warned residents may experience symptoms including headaches, eye and throat irritation, wheezing or chest pains.

Seniors, pregnant people, young children, people who work outdoors and those with existing health conditions are more likely to be impacted by the wildfire smoke. They're advised to avoid going outdoors and to seek medical attention if experiencing symptoms.

Toronto ranked fourth on Friday morning in a list of the world's most polluted cities, according to a global ranking by IQAir, a Swiss air quality technology company.