[Effect of nitrogen oxides and suspended dust in the air on the incidence of inpatient treatment of children with stenosing laryngotracheitis (pseudocroup). Results of an 8-year epidemiologic retrospective study based on inpatient case figures and area-related data of air measurements in the Bochum city district].

Results of a recently published study over a test period of 18 years showed no relationship between croup incidence of hospitalized children and SO2 levels measured in the city of Bochum. In the following study 642 hospitalized children with stenosing laryngotracheitis were examined for a possible time-dependent relationship between croup incidence and NO2, NO- and dust immission levels measured in the city of Bochum (approx. 1000 000 readings). Evaluation of a 6-year period yielded a decrease of croup patients for the lower NO2 concentration range and a statistical increase of croup cases during days with higher NO2 concentrations. However no cause-effect relationship between both variables can be established because other determinants like infections, temperature, weather change influences, in door pollution etc., could not be excluded. Evaluation of NO levels over 3 years and dust levels over a test period of 1 year showed no statistical relationship with corresponding croup incidence.