Alerting Canadians of Atmospheric Risks

UV, Air Quality, Wind Chill and Heat Indexes

Canada operates networks that measure atmospheric conditions across the country. Scientists at the Meteorological Service of Canada MSC, working with health scientists and others, have used the data from these networks to develop indexes that alert Canadians to atmospheric conditions that pose a risk to their health and wellbeing.

UV Index

Ultraviolet (UV) radiation from the sun can harm a person’s skin, eyes and immune system. It is estimated that over 800 Canadians will die from malignant melanoma and that some 72,000 will develop other sun induced skin cancers each year.

Based on a decade of UV data collected at the 12 Canadian monitoring sites, MSC scientists developed the UV Index, which provides a measure of the intensity of the sun’s ultraviolet radiation. In 1992, the MSC started using the UV Index in its weather models to forecast the next day’s UV levels. Canada was the first country in the world to introduce these forecasts, which have raised public awareness of the health hazards associated with prolonged exposure to UV. People are now more likely to take preventitive actions to reduce the likelihood of developing skin cancer or cataracts.

Air Quality Index

Poor air quality, especially fine particles and ground-level ozone, affects respiratory health and contributes to hundreds of premature deaths each year in Canada. It also impairs visibility and adversely affects materials and the natural environment.

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A chart of the annual UV (ultra violet) index maximums for Toronto, Ontario for the year 2002.

Smog can occur in the summer or winter, though more often on hot still days. People can take action to reduce their exposure to poor air quality if they know about it. Health Canada and MSC scientists are working with provincial and other experts to develop a health risk based air quality index that can be used to provide consistent information to the public across Canada.

Heat-Health Alert System

The elderly and individuals with pre-existing medical conditions are particularly vulnerable to heat-stress. MSC scientists collaborated with health scientists to develop a heat alert system that links mortality rates with weather data. During its first summer of operation in Toronto in 2002, 4 heat alerts and 1 heat emergency were issued. The alerts triggered the city to respond by distributing water to vulnerable sectors of the population, and to open air-conditioned facilities to the public for relief from the heat.

Wind Chill Index

Each year, more than 80 Canadians die from over-exposure to the cold, and many more suffer injuries from frostbite and hypothermia. The combination of cold temperatures and strong wind speeds up the rate at which the body loses heat resulting in wind chill. MSC worked with scientists in the U.S. and human physiologists to develop a new Wind Chill Index. This new index was implemented in October 2001 throughout North America, and expresses wind chill as an equivalent temperature.

MSC scientists working in conjunction with health scientists, and across governments, have brought the science of solar radiation, air quality, and temperature extremes to the Canadian public in a relevant, credible and understandable way - enabling Canadians to make informed choices to protect themselves from the risks of atmospheric threats.

“The UV Index has been a great help in raising the awareness of Canadians to the risks of UV exposure.”
Michelle Albagli
Executive Director Canadian Dermatology Association

Meteorological Service of Canada - Environment Canada - Government of Canada

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