We also use outdoor monitors to represent exposure to the infants.
For example, epidemiology studies frequently use a central site monitor to represent air quality for a given area or an agglomeration of monitors across a city.
Thus, in general, for spatially variable species, a greater amount of measurement error could be present when using a single monitor to represent exposure over an entire community.
Furthermore, the limitations of using fixed monitors to represent the entire population in environmental exposure studies have been frequently discussed (Goldberg et al. 2001).
Hourly measurements of the individual pollutants were averaged across multiple monitors, to represent exposure across the city for a given day.
Recognizing the limitations of personal monitoring and uncertainties associated with the use of central-site monitors to represent personal exposure to ambient air pollutants, the implementation of an exposure supersite program may be warranted.
First, large exposure measurement errors were likely, owing to the use of one to three monitors to represent exposure in these counties, some of which extend over thousands of square miles.
Epidemiologic analysis of the effects of particulate matter constituents is hindered by their spatial heterogeneity and the reliance on a few fixed-site monitors to represent exposures in large metropolitan areas.
Although these buffers were an improvement over studies using a single or multiple monitors to represent exposure over large metropolitan areas, they may not sufficiently measure concentrations of many of the PM constituents, such as elemental carbon (EC) and transition metals that are known to exhibit high spatial variance.
27 Second, we used fixed monitoring sites to represent air pollution and so may not accurately reflect personal exposure.
