Estimating human exposure to nitrogen dioxide: an indoor/outdoor modelling approach.

Human exposure to nitrogen dioxide can have adverse health effects. Policymakers need accurate information on the number of people exposed, the severity and patterns of exposure and the health-related effects of the exposure, in order to assess health risks and bring in appropriate control strategies. Data from central monitoring sites have been used in the past to establish air pollution exposures. Attempts to provide a realistic estimate of nitrogen dioxide exposures. Develops a simple deterministic model which relates exposure to background ambient levels, indoor values, and human activities. Monitoring programmes in six US cities were used for the ambient and indoor parameters. The study found that indoor nitrogen dioxide concentrations in residential buildings vary primarily with outdoor levels and type of cooking fuel, and influenced also by other factors such as air exchange rates and strength of indoor sources. Observed distributions of NO2 concentrations from outdoor and indoor setting are used to obtain estimates of population exposures, combined with information about number of people and time spent in the various microenvironments.