Which statement correctly distinguishes area sampling from personal sampling in air monitoring?

• A. Area sampling measures ambient concentrations in a space; personal sampling measures air in the worker's breathing zone.
• B. Area sampling measures air in breathing zone; personal sampling ambient.
• C. Area sampling is more accurate for individual exposure.
• D. Personal sampling uses stationary monitors.

Answer: (A)

In air monitoring, area sampling and personal sampling serve different purposes. Area sampling measures ambient concentrations in a space—using stationary monitors placed in the environment to characterize the general air quality of that room or area. Personal sampling, on the other hand, uses devices worn by the worker to sample the air in the breathing zone as the person moves and works, thereby reflecting the actual inhaled exposure. Because exposure depends on a person’s location and activity, personal sampling provides a better estimate of individual exposure, while area sampling informs about the environment as a whole.

The other ideas mix up where the samples come from or who they represent: area sampling isn’t measuring the breathing zone, and personal sampling isn’t limited to stationary devices.