Acute effects of ambient air pollution episodes on respiratory health of children

In this thesis the acute effects of air pollution episodes on respiratory health of seven to eleven year old children living in non-urban communities in the Netherlands are discussed. Repeated measurements of pulmonary function (spirometry) and the occurrence of acute respiratory symptoms using a daily diary, were conducted to detect health effects. Exposure to air pollution was characterized by the ambient concentration of several pollutants, including ozone, PM _{<font size="-2">10</font>} and acid aerosol, measured at fixed sites. Data were collected for a period of three and a half year, including two summer and three winter periods, from 1851 children.In the summer of 1989 several photochemical episodes occurred with one hour maximum ozone concentrations between 160 and 240 μg/m <sup><font size="-2">3</font></SUP>. During these episodes small decrements of pulmonary function persisting for at least one day were found. No evidence of increased respiratory symptoms was found during these episodes. No major winter air pollution episode occurred, but significant associations of pulmonary function with the concentration of particles smaller than 10 μm (PM _{<font size="-2">10</font>} ) were found. These associations were not explained by exposure to acid aerosol, because concentration levels of acid aerosol were low during both the winter and the summer periods. For the general population samples of children, respiratory symptom prevalence was not associated with air pollution levels. For a panel of children with chronic respiratory symptoms, prevalence of wheeze and bronchodilator use was associated with the PM _{<font size="-2">10</font>} concentration. For all study populations differences in pulmonary function response between individual children were found. However, determined characteristics of the children (age, gender, presence of chronic respiratory symptoms) did not explain the magnitude of the response to air pollution.The findings of the present study in combination with other recent studies support a revision of present guidelines for ozone and particulate matter.