Estimating human exposure to nitrogen dioxide: Results from a personal monitoring study among housewives

Weekly average personal exposure to nitrogen dioxide (NO₂) was measured in a population of housewives living in Wageningen, The Netherlands, together with weekly average indoor NO₂ concentrations and indoor NO₂ peak concentrations. In part of the population the personal exposure measurements were repeated. The personal exposure and the indoor concentrations were in line with those in other studies in Holland. In general they were higher than the levels found in studies in the United States and Canada, but lower than those reported for Great Britain and Japan. The NO₂ peak concentrations were high, especially in the kitchen. Relationships between personal exposure and indoor concentrations were investigated using bivariate and multiple regression techniques. Indoor concentrations were found to be highly related to personal exposure. The contribution of peak concentrations to the explanation of personal exposure was small. An analysis of variance of the repeated personal exposure measurements showed that due to variation of personal exposure in space and/or time the "error" variance (within persons) was almost as large as the "true" variance (due to differences between persons). Therefore, it will be necessary to repeat personal exposure measurements in order to obtain reliable exposure estimates in health effect studies.