Air Pollution and Allergies: A Connection?

Medical Author: Alan Szeftel, MD, FCCP
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

Does the "air we breathe" have an impact on the rising incidence of allergies and asthma? Hay fever was rare in Japan before World War II. However, pollen allergy is now common and mostly affects those living in Japanese cities and near highways. Allergic disease is also more common in highly developed countries in North America and Europe and less common in Third World countries. This suggests that there must be something about modern, urban life that promotes allergy. Let us examine the impact of air pollution.

By far the most important indoor pollutant is tobacco smoke, which is strongly associated with allergic sensitization, asthma, and other respiratory illnesses. Exposure to smoke results in the body's enhanced ability to produce IgE (the allergy antibody) that attaches to allergens (e.g. pollen, dust mites and dander). The IgE response is a key trigger of allergic reactions. Parental smoking increases the risk of their children having many respiratory illnesses, including bronchitis, chronic cough, and asthma. Smoking during pregnancy and breastfeeding results in a higher risk for the children to develop allergic eczema (atopic dermatitis). The rate of asthma in an infant of a smoking mother is double that of a non-smoking mother. This is very important, since in North America, 25% of mothers smoke during pregnancy and 40% have a smoker in the home.

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