The smoggy sky has passed, but what caused it?
Environment Canada claim vehicles and our industrial areas were to blame for Tuesday’s (Mar.13) special air quality statement.
"All the exhaust from the cars driving around, especially around rush hour cause pollutants in the air and those built up instead of blowing away or being mixed into the atmosphere," said meteorologist John-Paul Cragg.
A stagnant air mass also pushed the problem. Air stagnation is when light winds and pressure systems make the air sink, leading to pollution building up near the ground.
"Industrial areas and any electricity generation by fossil fuels all together with the pollutants they generate would have helped to deteriorate the air quality."
Cragg added that this is most common to happen in the late winter or early spring.
Those with health problems are especially at risk.