There are also "masks" you can wear that help you pre-warm the air you're breathing in. Lots of winter sports folks use them since not only does cold air worsen EI asthma, it can also cause it. Cross-country skiers (purportedly _the_ most aerobic form of exercize, with swimming and biking right up there alongside) sometimes develop EI asthma after years of breathing in bucketsfull of very cold air. On the other hand, my son who had EI asthma his first couple seasons as a cross-country skier trained his way out of it. As his lung capacity increased, his need for medication decreased and finally disappeared. My 2c worth: Have medication available and use as needed; remember to warm up; try also a light mouth-mask so you get warmer, damper air in your lungs; train indoors on the coldest days; but don't give up training in the winter.