How Cold Weather Can Affect Air Quality

Posted on November 13, 2015

Winter in Alberta can result in some very cold weather, keeping even those who love wintertime bundled up and indoors. A drop into the deep freeze often restricts our activities, and it can also affect the quality of the outdoor air.

Most of the time, local air quality in this region is of low risk to health as indicated by the Air Quality Health Index (AQHI). However, the AQHI rating can rise to a moderate or high health risk when there is an occurrence of a weather phenomenon called a temperature inversion.

Temperature Inversions

Normally, warm air sits near the ground and air rises easily, carrying away and dispersing polluting substances. During a temperature inversion, cold air is trapped near the ground by warm air up to several hundred meters above it. The warm air acts like a lid and polluting substances can’t rise and disperse as readily. This often leads to increased AQHI ratings.

Some sources of polluting substances, like industrial emissions and wetlands, stay fairly constant throughout the year no matter what the season. But in the winter, fireplaces, wood stoves, home heating and idling vehicles contribute to higher concentrations. A temperature inversion traps a build-up of these substances near the ground until wind, a snowstorm or some other weather change sweeps them away.

Fortunately, temperature inversions that cause high or very high AQHI ratings are rare. For example, in 2019, FAP measured only 175 hours of high or very high AQHI ratings out of a total of 56,085 monitoring hours (102 of these were due to wildfires in May).

The AQHI is a tool that helps people understand what the local outside air quality means to their health. An outdoor activity recommendation corresponds to each risk category. Moderate to high AQHI ratings may lead to health problems for at risk populations, such as children, the elderly and those with pre-existing respiratory conditions.

What You Can Do

People can reduce their impact on air quality by not idling vehicles when parked, avoiding excessive fireplace or wood stove use, and using energy efficient products. People can also keep track of current and forecast local AQHI levels on the home page of our website and, if levels are high, adjust their outdoor activities accordingly.