The International Study of Asthma and Allergies in Childhood (ISAAC): objectives and methods; results from German ISAAC centres concerning traffic density and wheezing and allergic rhinitis.

The International Study of Asthma and Allergies in Childhood (ISAAC) was founded to maximize the value of epidemiological research into asthma and allergic disease by establishing a standardized methodology and facilitating international collaboration and comparison of data. The ISAAC design comprises three phases: Phase I uses validated core questionnaires designed to assess the prevalence and severity of asthma and allergic disease in defined populations; Phase II will investigate possible aetiological factors suggested by findings of Phase I and apply lung, blood and skin tests; Phase III will be a repetition of Phase I after 5 years to assess time trends in the prevalence and severity of wheezing, rhinitis and eczema in each ISAAC centre. In 1991 a survey on wheezing and allergic rhinitis in 2050 12-15 year old adolescents in Bochum showed a positive correlation between the prevalence of wheezing as well as allergic rhinitis and indicators of traffic density, controlling for putative confounders such as age, sex, passive smoking, active smoking, etc. In 1994-1995 an ISAAC Phase I survey conducted on adolescents in Münster, applying methodology similar to that in Bochum, found positive associations between surrogate measures of traffic density and 12 months prevalence of wheezing and lifetime prevalence of allergic rhinitis of a magnitude very close to that found in Bochum. The results from the two German cities provide support to the hypothesis that exposure to automobile emissions is related to wheezing and allergic rhinitis in children.