Prairie wildfire smoke is causing poor air quality in Hamilton, southern Ontario: Environment Canada

Smoke from wildfires in the Prairies is causing poor air quality and reduced visibility in the Hamilton-Niagara area and much of southern Ontario, Environment Canada says. 

The federal agency says people should limit time outdoors and consider rescheduling outdoor activities. 

Its special weather statement covers the southwestern part of the province from Sault Ste. Marie and Parry Sound, south to the Great Lakes and as far east as Kingston. Most of northwestern Ontario is also affected. 

Smoke levels can change hourly and "as smoke levels increase, health risks increase," Environment Canada said, adding air quality is expected to improve from north to south today.

LISTEN | What to keep in mind as wildfire smoke affects air quality: 

5:59As smoke reduces air quality, here's what to keep in mind.

Much of northern Ontario is under air quality statements, or more severe warnings, due to wildfire smoke. We’ll hear from Stephanie Charles of the Northwestern Health Unit about how poor air quality can affect people’s health.

In Hamilton, the air-quality health index is forecast to reach seven Thursday, which is considered "high risk," before dropping down to a "moderate" four overnight. 

Smoke can cause eye, ear, nose and throat irritation, headaches or a mild cough, Environment Canada says. It can also cause chest pains and wheezing.

The agency says seniors, pregnant people, kids and babies, people with health conditions and those who work outdoors should reduce activity outdoors and seek medical help if experiencing symptoms.

It adds that when indoors, people should keep their windows closed as much as possible, but that during extreme heat, it's best to prioritize keeping cool. 

LISTEN | Gardens in need of extra care due to wildfire smoke: 

Up To Speed7:30Gardens in need of extra care due to wildfire smoke

The wildfire smoke can affect the air quality, and that can put stress on your garden plants. CBC's Up to Speed guest host Laurie Hoogstraten gets some tips on how to help them thrive in the smoky conditions. Hoogstraten spoke with Sajjad Rao, research professor at Assiniboine College's Russ Edwards School of Agriculture & Environment in Brandon.

Hamilton was just under a heat warning, which the medical officer of health ended Thursday morning. 

Wearing a respirator and using an indoor air cleaner are ways Environment Canada says one can reduce exposure to pollution.