Smog Advisories

Smog (a concentration of smoke and fog) is ozone (O₃), fine particulate matter (PM_2.5) and other contaminants that mix in the atmosphere. Smog advisories are issued by the Ontario Ministry of the Environment when elevated pollutant levels occur (Air Quality Index indicates a poor level) or are predicted to occur and/or will persist for several hours.

The number of smog advisory days varies from year to year, primarily due to weather conditions. During the hot, humid conditions of 2005 there were a greater number of smog advisory days compared with the cooler, cloudier summers of 2004 and 2006. Although most smog days occur in the summer months it is important to note that smog can occur even in winter.

In the last 5 years in Simcoe Muskoka, 2005 recorded the largest number of advisory days and smog advisories. 2007 had the second largest number with 9 advisories issued lasting a total of 27 days.