A temporary decrease in the ventilatory function of an urban population during an acute increase in air pollution.

During a short period of increased air pollution in a polluted area in the Netherlands, a majority of the inhabitants showed a lower VC and FEV1 value than during a period of extremely low pollution. This may be due to a temporary decrease in the ventilatory function in response to a temporary increase in air pollution. Persons who showed the greatest "decrease" in the VC and/or FEV1 had a slightly higher prevalence of chronic non-specific lung disease (CNSLD) than did those who had a slight or no decrease in VC and FEV1. The studies will be continued in order to determine whether the groups will show different repiratory disease patterns in the future. In studies on long-term effects of exposure to air pollution, one must consider the possibility that short-term effects may influence the results of the lung function measurements. It is always important, therefore, to include a questionnaire on respiratory symptoms in such studies, since it is unlikely that short periods of air pollution influence the prevalence of chronic respiratory symptoms.