Effects of sulfur dioxide and smoke on the incidence of laryngotracheitis (croup).

During the 1981-1990 period, 652 children, 70% boys and 30% girls, were hospitalized at the Zagreb University ENT Department for laryngotracheitis (croup). Most of the children were hospitalized at the age of 2, and 90% of all children were under the age of 7. The highest number of cases of laryngotracheitis were admitted during autumn, especially in October, and the lowest in July. No correlation was found between the mean and peak monthly values of sulfur dioxide and smoke in the air in Zagreb and the number of children hospitalized for laryngotracheitis.