You may still feel hot and bothered this week even though the heat wave is gone because you’ll still be breathing in smog.
The warm – but not quite heat-wave warm – temperatures expected for the GTA this week are a result of light winds pushing hot, southern air from the Ohio Valley, said David Phillips, senior climatologist for Environment Canada.
It’s this same air that is shoving extra pollutants to our already dirty airspace. “It’s the chemistry that takes place in the atmosphere, with the sun and the heat, that brings smog on faster,” he said.
All of these air impurities wouldn’t be a problem if rain or wind would sweep through the city, but neither is expected in the next few days, said Phillips. This morning's air quality index was 24, which means it was still considered good according to the Ontario Air Quality Index, but approaching moderate levels.
For it to improve dramatically, we need rain and wind. Rainfall not only lowers the temperatures but also scrubs the air clean of the toxins that build up from air emissions. But Phillips says that wind is the true solution to smoggy days because it disperses and ultimately pushes the stale, dirty air out of the city.
Take July 7, for example, the third day last week when Toronto saw temperatures above 33 C. It was the worst day during the heat wave in terms of smog – recording an air quality index of 59, which Ontario’s Environment Ministry classifies as air so poor to inhale, it can have adverse effects on our health.
But July 7 was not the hottest day of the heat wave – that was July 5 when temperatures rose to 34.1 C – but it was the least windy day. Gusts of wind that day never went faster than 31 km/h.
Phillips explained that the lack of wind meant more pollutants gathered, baked under the sun and worsened the air quality, even though it was slightly less warm.
Since this past weekend’s rainfall, when most of the heat wave smog was washed away, the air quality index has been rising, along with temperatures. There is a connection between the two factors according to Phillips, but not a correlation.
Unfortunately for residents in polluted areas, the only way to get rid of the smog is to kiss goodbye the sunshine and wish for rain and wind.
--Madeleine White
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