Several communities in southwestern Ontario were put under a special air quality statement as hot and humid weather conditions were expected to create elevated pollution levels.
Environment Canada issued the advisory late Tuesday morning for Sarnia-Lambton, Chatham-Kent, Windsor-Essex, Goderich, and southern Huron County.
The national weather agency said high levels of air pollution are possible Tuesday afternoon and into the evening hours.
At around 8:30 p.m. Tuesday, the advisory ended.
Wednesday's high is expected to be around 30 C, 86 F.
