How do passive badges differ from active sampling methods?

Passive badges differ from active sampling methods primarily in that they rely on diffusion to collect air samples. In passive sampling, the collected air contaminants enter the badge through diffusion without the need for mechanical assistance, such as a pump. This process allows for a more straightforward measurement technique, as the passive badges can simply be worn by the worker over a designated period to collect samples based on the concentration gradients of the target analytes.

Active sampling, on the other hand, generally uses a pump to actively draw air through a collection medium, allowing for real-time sampling and usually higher precision in quantifying air contaminants.

The other options highlight characteristics that do not accurately characterize passive badges. The cost associated with passive badges can vary, but they are typically less expensive than the equipment needed for active sampling methods, such as pumps. Passive badges do not require any mechanical devices to operate, which further distinguishes them from active methods. Additionally, passive badges are not utilized for surface sampling; their primary function is to collect airborne contaminants, contrasting with active sampling that may cover various types of media. Thus, reliance on diffusion is the defining feature of passive badges.