Environmental Trends 2002

Health and Environment

What is the UV Exposure of British Columbians?

UV Index Over Southern British Columbia

SOURCE: Environment Canada. World Ozone and Ultraviolet Radiation Data Centre 2002. NOTES: *Data for 2001 are preliminary. The scale used for the UV Index is: Low (0-3.9), more than one hour to burn; Moderate (4-6.9), about 30 minutes to burn; High (7-8.9), about 20 minutes to burn; and Extreme (9+), 15 minutes or less to burn. Missing days were due to mechanical failure or extremely rainy or overcast weather.

What are the risks to UV exposure in British Columbia?

• The UV Index measures the intensity of ground-level ultra-violet radiation (UV) on a scale of 0 to 10.

• Ground–level UV varies with the seasonal angle of the sun’s rays, the thickness of the ozone layer, and the weather. Cloud cover and rain can greatly reduce UV, even in the summer.

• UV intensity in British Columbia is at its highest in the summer. In June and July, the UV Index value for a clear day is usually between 7 and 8.

• Under normal ozone levels, the UV Index over southern British Columbia ranges from under 1 in winter, to 4-5 in late spring and early fall, to 7 in summer.

• In 2000, the UV Index for southern British Columbia was greater than 7 on 48 days, and greater than 9 on 2 days. According to preliminary data for 2001, the UV Index for southern British Columbia was greater than 7 on 23 days, but never greater than 9.

For detailed information, including graph data, see In-Depth report [pdf].