On his summer vacation in 2001, Pierre Tourigny went for a walk in a refrigerator.

In fact, the meteorologist took several 90-minute walks on a treadmill in a refrigerated wind tunnel at the Defence and Civil Institute of Environmental Medicine in Toronto, not far from his usual Environment Canada office.

Tourigny was one of 12 volunteer guinea pigs, six men and six women, testing a new way to measure and report wind chill, the combined cooling effect of low temperatures and wind.

The volunteers were wired with a battery of temperature sensors at different points on their faces and inside their mouths, and even rectal probes to monitor core body temperature.

"In the end, it was the mouth probe that I found most annoying because it prevented me from opening my mouth," said Tourigny. "You should have seen me with all these sensors and wires: I looked like a robot."

Each volunteer took one walk at -10 degrees C, one at 0 degrees and one at +10 degrees, plus a "wet trial" at +10 degrees with a light one-second splash of water in the face every 15 seconds. The walks lasted 90 minutes each -- 30 minutes for three different wind speeds: about 8, 18 and 29 kilometres per hour, respectively.

The wet trial was the most uncomfortable, Tourigny said.

"I had a surprise at each spray, at least for the first minutes. Let me just say I was glad they did that trial at +10 and not at 0 as was first envisaged: the water really felt cold at times!"

Why go to all this trouble? After all, we've had wind chill measurements and wind chill reports for decades.

The new approach to wind chill is partly the result of new science and partly a response to Canadians' dissatisfaction with the way wind chill was being reported, said Bill Miller of Environment Canada in Whitehorse. Concerned that Canadians did not understand the way wind chill has been reported for the past few years, in watts per square metre, Environment Canada conducted a major study, across Canada, to find ways to make the reporting more relevant and accessible.

"Focus groups in Haines Junction and at Kwanlin Dun, along with phone surveys of over 300 Yukoners, helped us to understand the needs of northerners," Miller said.

Changing the way wind chill is reported was not enough, he said. The old standards were misleading as well as confusing.

The concept of wind chill dates from 1939, when Antarctic explorer Paul Siple worked out a way to express the fact that you get cold faster if the wind is blowing. He measured the freezing rate of water at a height of 10 metres above the ground, where anemometers are placed to measure wind. However, most of us live a lot closer to the ground, where the wind behaves differently, and our faces don't freeze in the same way water does.

So the researchers developed a new formula to estimate the actual effect of wind and cold temperatures on exposed skin. They began by testing temperature changes on a mannequin head with a skin made of special thermoconducting material. Then they tested the mathematical model derived from the mannequin head on human subjects, including Pierre Tourigny.

They found a considerable difference in the way individuals respond to cold and wind. More than half the people in the test proved to have a physiological adaptation that sends a flush of blood to the facial skin when it drops below a certain temperature. However, in order to protect the people most vulnerable to frostbite, the researchers adjusted their formula to the portion of the population who experience the greatest facial cooling.

While there is still more to learn about wind chill, the new formula is now in use, along with a new way of expressing wind chill. Environment Canada forecasters will be reporting wind chill in "feels-like" terms that approximate temperature -- that is, a wind chill of minus 30 means it will feel like -30 degrees Celsius, even if the actual temperature is only -20 degrees.

The mathematical formula behind wind chill, and an explanation of it, are on the internet at www.msc.ec.gc.ca/windchill/Science_equations_e.cfm. Even better, if you don't want to do the math yourself, Environment Canada has provided a handy little wind chill calculator at www.msc.ec.gc.ca/windchill/calculator_e.cfm.

For information about wind chill, go to www.msc.ec.gc.ca/windchill. For current temperatures, wind chill and forecasts, call 668-6061 in Whitehorse or 993-8367 in Dawson City.