Respiratory symptoms and atopic sensitization among school children in different settings around the Baltic Sea

Abstract: The aim of this thesis was to assess the prevalence of respiratory symptoms and atopic sensitization and related risk faCtors amo:Og school children in urban and rural areas of Sundsvall in Northern Sweden and urban areas of Konin in Poland and Tallinn and Tartu in Estonia. Ambient levels of N02 were similar in urban Sundsvall and Konin whereas levels of S02 and smoke were about 5 times higher in Konin than in Sundsvall. Children in Estonia and Poland had a lower standard of living and were more exposed to indoor air pollutants.Among 10 527 school children in Sundsvall aged 7-16 years the prevalence of asthma was 4% in 1985. No differences were seen between urban and rural Sundsvall. School absenteeism due to asthma was uncommon.The prevalence of positive skin prick tests in 642 school children (aged 10, 12 and 14 years) from urban and rural areas of Sundsvall was detem1ined in 1988. In this study, urban living was a risk factor for at least one positive skin prick test to pollen or animal dander, OR 1.83(95% Cl 1.26- 2.67). The increased risk was only demonstrated among children with atopic heredity. Passive monitoring of nitrogen dioxide in Sundsvall showed that urban children as compared with rural children were exposed to higher levels of NC>z (13 ;tglm3 and 7 ;tglm3, respectively). The children spent 90% of their time indoors. The most important source of exposure were the indoor skating arenas, where levels up to 8()(X) ;tglm3 were measured during 1-hour periods.Parental questionnaires, skin prick tests and serial peak flow measurements for a period of 2 weeks were used in the next study involving 2594 10-12 year old children from Sweden, Poland and Estonia. Respiratory symptoms were common whereas positive skin prick tests were uncommon in Poland and Estonia. The risk for positive skin prick test was decreased in Konin, OR 0.58 (95% CI 0.37- 0.91) but increased in urban Sundsvall, 1.67 (95% Cl 1.15- 2.42) (rural Sundsvall reference group). The odds ratios in Estonia were similar to Poland. Current maternal smoking had a strong dose-resp.:mse association with current coughing attacks but only in Eastern Europe. An inverse relationship was recorded between domestic crowding and sensitization, the risk of scnsitization increased as the number of persons in the household decreased (OR 0.58, 95% Cl 0.43- 0.77).The study suggests that factors related to domestic crowding protect against atopic sensitization in Estonia and Poland. In Sweden, by contrast, an increased standard of living with less crowding and less infections is associated with enhanced vulnerability to air pollutants andother adjuvant factors.