When the mercury on your thermometer sinks during the winter in Alberta, it has you reaching for your warmest winter jacket and forces school recess indoors. Frosty temperatures can also influence air quality. Most of the time, local air quality is of low risk to health. However, it can rise to the medium and even high risk range due to cold weather, even if only for a few hours.
Measuring air quality
Local ambient air quality is measured by a network of air monitoring stations throughout the region. It is then categorized into Low, Moderate, High or Very High Risk to health by the Alberta Air Quality Health Index (AQHI).
Some sources of pollution, like industrial emissions, stay fairly constant throughout the year, no matter what the season. But roaring fireplaces, wood stoves and idling vehicles in the winter all contribute to higher levels of very small particulate matter and other pollutants. Cold temperatures and stagnant air can create a build-up of these substances near the ground.
When AQHI values increase in the winter, it’s generally due to a weather condition referred to as a temperature inversion. Normally, warm air sits near the ground and the air can rise easily and carry away pollutants. During a temperature inversion, cold air is trapped near the ground by a layer of warm air several hundred meters above it. The warm air acts like a lid, meaning pollutants can’t rise and disperse as readily, leading to higher AQHI readings. Moderate to high AQHI readings may lead to health problems for “at risk” populations, including children, the elderly and those with existing respiratory issues, according to Alberta Environment and Parks.
From an air quality perspective, storms and high winds are a welcome weather event. Wind, rain and snowstorms are sometimes called scrubbers because they help clear out and disperse accumulated substances. People can help reduce their impact on air quality by carpooling, not idling when parked and working from home when levels are high.
Current and forecast local AQHI levels are available at fortair.org. The public can also view near real time hourly readings from all eight of Fort Air Partnership’s continuous monitoring stations.