Air quality warning downgraded to yellow, thunderstorm warning issued across Greater Toronto Area

environs Canada downgraded an on-going transmit lineament warning and issued a terrible thunderstorm warning across the Greater Toronto Area for strong winds, large hail and heavy rain on Saturday.

The national weather agency issued a yellow-level warning for thunderstorms starting around noon that could produce wind gusts up to 110 kilometres per hour, hail the size of quarters to ping pong balls and rainfall amounts up to 40 millimetres.

It said a cold front over Michigan was bringing in "a line of thunderstorms" that would travel southeast across the region. Residents are urged to stay indoors if they hear thunder and to be aware of difficult driving conditions.

Environment Canada also downgraded it's air quality warning from orange to yellow across the GTA. The "poor" air quality warning was issued after smoke drifted south from wildfires in northwestern Ontario.

Earlier on Saturday, the weather agency said smoke levels were expected to increase at night.

Showers and thunderstorms are expected to "help sweep out" the smoke temporarily on Saturday, said meteorologist Rob Kuhn on Friday.

On Saturday morning, Toronto topped the list of the world's most polluted cities, according to a global ranking by IQAir, a Swiss air quality technology company.

The air quality health index (AQHI) at 10 a.m. Saturday was at 8 for "high risk" across Toronto and was at 5 or 6 for "moderate risk" in Brampton, Oakville, Mississauga and Oshawa.

Concentrations of fine particulate matter from the smoke, known as PM 2.5, were at high levels on Saturday morning after they had dropped drastically on Friday. These airborne particles are less than 2.5 micrometres in diameter, smaller than a strand of human hair, and can travel deep into your lungs.

As of 10 a.m. Saturday, here is how much PM 2.5 is in the atmosphere for some GT municipalities:

Toronto's air quality expected to worsen. Here's what you need to know

Toronto is reopening outdoor and wading pools at 2 p.m. Saturday due to improving air quality, said the city in a news release.

FIFA Fan Festival is also expected to have a delayed start at 3:30 p.m. Due to severe weather, it said.

The city added that it may suspend outdoor services again depending on evolving weather and air quality conditions.

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

'Very poor air quality' in store for GTA Friday night, possibly Saturday as wildfire smoke returns

Organizers with BIG on Bloor and Beaches Jazz Festival said on social media that events would proceed as planned, despite the air quality warnings.

"Forecasts indicate that conditions are expected to improve as Saturday progresses, and our team will continue monitoring updates," said the team behind BIG on Bloor.

Meanwhile, Toronto Caribbean Carnival Junior Carnival Parade was rescheduled from Saturday to Sunday due to inclement weather forecasts.

"The decision has been made with the safety and comfort of the thousands of young participants, their families, volunteers, spectators and event staff as the highest priority," said event organizers in a news release.

Toronto has six "cleaner air spaces" open at city hall, Metro Hall, North York Civic Centre, Scarborough Civic Centre, York Civic Centre and East York Civic Centre.

Environment Canada says 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.

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