And all based on a faulty premise. Therefore, any direct comparison would not be a proper use of the information and would produce inaccurate findings. Common sense indicates as much. If air pollution were the culprit, asthma rates hardly would rise as air becomes cleaner. It is true that asthma is becoming almost epidemic.
Scientists have several theories about what is causing the increase.
That explains why asthma rates are rising most rapidly among inner-city dwellers and children. Doctors also theorize that asthma is increasing because our immune systems aren't getting enough exercise. Modern life is sanitary. Lacking sufficient bacteria to prey upon, the immune system fights allergens. The increase in asthma could be an evolutionary phenomenon as well.