Overview of methods to assess population exposure to ambient air pollution

In an effort to support the adoption and implementation of the WHO Air Quality Guidelines, this document summarizes several air quality measurement and modelling methods that can be used to estimate ground-level air pollutant concentrations and presents multiple approaches to monitoring ambient air pollution at different spatial and temporal scales. These methods are crucial for estimating population exposures, which can be defined as the product of the pollutant concentration and the time over which a person is in contact with this pollutant. Air quality measurements and models are presented in order of increasing complexity/technology, starting with the least complex. For each method a brief description is provided followed by its strengths and limitations as well as a few examples of global or regional applications. A comparison with advantages and disadvantages for each monitoring method is then presented, followed by a brief discussion on exposure disparities.