Ultraviolet rays that can cause sunburn and skin cancer are at unusually high levels in Canada this year, due to record ozone loss above the Arctic this past winter, Environment Canada warns.

The ozone-depleted air above the Arctic is expected to work its way down to southern Ontario and is just getting into the area, Environment Canada meteorologist Geoff Coulson said Friday.

"It should be with us for the rest of the summer," he told CBC's Metro Morning.

Consequently, the federal department forecasts that UV levels will be "a little stronger than normal" — roughly three to four per cent higher than levels before 1980.

Coulson, who specializes in weather warnings and making sure people are prepared, said there have already been a few days the UV index has already been nine or very high in southern Ontario.

"There may be certain days in the coming weeks where we're going to have a UV index of 11-plus or extreme," he said.

Dr. Peter Vignjevic, a dermatologist and assistant professor of dermatology at McMaster University in Hamilton, Ont., said the best protection against the sun's UV rays is a physical barrier such as a wide-brimmed hat, long sleeves and long pants.

He recommends that for parts of the body where the skin is exposed, people use waterproof sunscreen with a sun protection factor (SPF) of 30 or more that is designed to block both types of ultraviolet rays, UVA and UVB.

Most people don't apply enough sunscreen

Vignjevic added that people need to apply about two to three teaspoons per arm and three to four per leg to be properly protected.

"Most people don't use it in nearly those amounts," he said. "Those are the amounts you need to use if you actually want to get the SPF that's on the bottle."

The record ozone loss in the Arctic has been caused by ozone-destroying chemicals such as chlorofluorocarbons and halons left over from before the Montreal Protocol. That was the international agreement signed in 1987 to phase out those chemicals, which were used in products such as refrigerators, aerosol spray cans, fire extinguishers.

Climate change is producing conditions in the atmosphere that enhance ozone-destroying chemical reactions. Greenhouse gases are trapping heat close to the surface of the Earth, preventing it from reaching the stratosphere above, where the ozone layer is found. Colder temperatures in the stratosphere boost ozone depletion.

Arctic ozone Move the slider up and down to compare the ozone above the Arctic in NASA images from March 2010 and March 2011