So what is the effect on high altitudes on asthma? If I board an airplane, will this make my asthma worse? What if you climb to the top of a mountain?

These are common questions I've had to answer over the years. In fact, when I traveled to Denver in 1985 to stay at the asthma hospital -- Denver is a mile high -- this was one of the questions my parents asked. 

If high altitudes affect your asthma, it's due to one of the following:

• Air is cooler and drier at higher altitudes. As I noted in this...