In asthmatics, the inflammation is to the inside of the airways within the lungs. As these airways get smaller and smaller, the effects of inflammation on the inner lining have a bigger and bigger impact. Environmental irritation causes contraction of the muscles that control the "openess" of these tubes, and if the space is small in the first place then they're only going to get really tight once they've been irritated!
So if you have a tendency to suffer from asthma and you're heading out into the "Great Outdoors", PLEASE go well prepared because sometimes you just don't know what might trigger that asthma attack and you might be a long way away from support and help. Simple things like insect bites, smoke from a camp fire, a fruit bar with nut oil, or even just a change in the weather can trigger an episode.
Prevention is the key to good asthma control. Getting any inflammation under control and making sure that you can avoid "Triggers" where possible are both fundamental to preventing a potentially serious asthmatic attacks. According to Dr. James Sublett, chairman of the American College of Allergy, Asthma and Immunology Public Relations Committee, "Planning ahead, seeing an allergist and knowing the causes of allergy and asthma, even those with the most sensitive noses and lungs can enjoy summer fun".