AIR-POLLUTION LEVELS, METEROLOGICAL CONDITIONS AND ASTHMA SYMPTOMS

We wanted to asses relations between the daily occurrence of asthma sy mptoms and fluctuations of air pollution concentrations and meteorolog ical conditions.In a panel of 31 asthmatic patients residing in the to wn of Pitea in northern Sweden, severe symptoms of shortness of breath , wheeze, cough and phlegm were recorded in an asthma diary together w ith suspected causes. Sulphur dioxide, nitrogen dioxide, black smoke, relative humidity and temperature were used to evaluate the relationsh ip to the environment. By using multivariate analyses, we found that d aily variations in the particulate pollution levels indicated by black smoke levels below the criteria limits, had significant effects on th e risk of developing severe symptoms of shortness of breath. This asso ciation was stronger among 10 subjects, who had at least five incident days with severe shortness of breath. Meteorological conditions were not significant in the multivariate models. Cough and phlegm did not s how significant relationships to any environmental condition that was evaluated. Only one-third of the subjects reported, at least once duri ng the study, symptoms believed to be related to air pollutants, altho ugh we found significant correlations between the pollution levels and the frequency of pollution-related symptoms. We conclude that an asso ciation has been established for black smoke as pollutant and shortnes s of breath as respiratory symptom, and that in certain asthmatics, ef fects were occuring at lower particulate levels than suggested previou sly.