2. Measurement strategy

The atmosphere is not homogeneous either in time or space: pollutant concentrations vary considerably from one point to another and from one moment to the next.

Similarly, each individual's space and time "budget" is highly variable: over the course of a day, each person is exposed to highly variable doses of pollutants, depending on their concentration at any given moment and the length of time they spend in each type of environment.

So, where, when, what to measure and why? Clearly, there is no single answer to these questions, and strategies can vary widely depending on the site...