Air pollution can also be considered a health risk for those living in Switzerland. During short episodes of high pollution (smog), protection from exposure can be recommended. The continuous air pollution problem, however, implies for the physician a complex educational task with regard to his patients. As the patient does not perceive a direct improvement in his personal health, it is difficult to promote ecologically acceptable behaviour. In view of the long term effects of continuous exposure to air pollution on the health of the population, such preventative activity is considered necessary.