What is the relationship between ambient levels and personal exposure to NO2?
The source document for this Digest states: Can the differences influence the results of studies? Answer: In any particular setting the answer will depend on the relative contributions of outdoor and indoor sources and on personal activity patterns. A direct relationship between personal exposure and outdoor concentrations is found in the absence of exposure to indoor sources such as unvented cooking or heating appliances using gas, and tobacco smoking. However, since outdoor NO2 is subject to wide variations caused by differences in proximity to road traffic and local weather conditions, the relationship of personal exposure to measurements made at outdoor monitoring stations is variable. Results of epidemiological studies relying on outdoor NO2 concentrations may be difficult to interpret if account is not taken of exposure to indoor sources. Rationale: An individual’s exposure to NO2 from outdoor sources will depend largely on their proximity to vehicular traffic in space and time,
