As we inhale through the nose, the air is filtered, warmed, and humidified in the upper respiratory area before it enters the lungs. Cold, dry air can trigger asthma symptoms, as the muscles around the airways constrict in reaction to the temperature of the air. If you need to be outdoors in cold weather, covering your nose and mouth with a scarf or mask can help raise the temperature of the air inhaled. While a certain amount of humidity in the air makes it easier to breathe, a very high humidity level can lead to hyperventilation, which can set off an asthma attack. Windy days can increase the levels of pollen, mold spores and other airborne irritants such as smoke.
Stagnant air can increase the levels of smog and other air pollutants.
Depending on your triggers, it may be best to exercise indoors, where weather conditions are less of a factor. When planning your daily activities, keep the weather conditions in mind as a factor in controlling your asthma. For others, exercise is an additional trigger for asthma symptoms. With exertion, the process of gas exchange in the lungs becomes more difficult. If our bodies are in good shape, we can exert ourselves more before our lungs need to work deeper and faster and likely have to breathe through the mouth, instead of the nose.