[Prospective one-year epidemiologic longitudinal study of air pollutants and the incidence of croup].

Among a population of 18,175 children below 7 years of age in medium sized towns and rural areas in south-western Germany 552 (3.03%) cases of croup were registered during a 12 months period in 1984-85 by their physicians. Distributions according to months, sex and age at the onset of the disease were the same as in other recent investigations: The level of the air-pollution measured (SO2, NOx, CO, CO2, ozone and dust) was low (highest monthly means in microgram/m3: SO2 88, NO2 73, NO 119, dust 41). There was no relevant influence of the degree of air pollution on croup-frequency. The rise of croup-frequency shortly after a period of several days of higher pollution was accompanied by an influenza epidemic as proved by virus isolations.