Environment Canada urges residents to limit their time outdoors. But even when inside, most buildings can only reduce airborne pollutants by half.

Environment Canada is warning of poor air quality and extreme heat in Toronto on Monday as southern Ontario braces for a week filled with hot and humid weather.

Toronto and the GTA are under a heat wave and poor air quality warning issued by Environment Canada on July 14, 2025, due to wildfire smoke from northern Ontario. The poor air quality is expected to persist from Monday into Tuesday.

The poor air quality that has blanketed swaths of central and Western Canada is not only infiltrating the lungs, but also distressing the mind.

With various air quality indexes available, and as wildfire smoke becomes an increasing health risk, here’s what often goes into the decision to play sports or not — and how to make sense of air quality indexes when making your own decision.