According to this study, the number of adults suffering from asthma has more than doubled in the last 2 decades, with steroid prescriptions increasing 6-fold. According to this study:

• The main reason for the asthma increase is allergies.

• Among people who never smoked the rate of hay fever (a type of allergy) went up from 6% to 20% and the rate of asthma increased from 3% to 8%.

• Among smokers, hay fever rose from 5% to 16% and asthma went up from 2% to 5%.

• The number of prescriptions for inhaled steroid medications for asthma has increased more than 6 times in the last decade.

British Medical Journal July 8, 2000;321:88-92.