Charge-based personal aerosol samplers.

There are several good reasons to use personal monitors for exposure control and health effect studies. But current personal monitoring methods are either not sensitive enough to measure typical ambient concentrations, work offline (masking short exposures to high concentrations), and/or require trained personnel to analyze the data, which makes them difficult to use. For this reason, we propose the use of a diffusion charging sensor as an online personal monitoring method, and present a miniaturized device (45 x 80 x 200 mm, 770 g) that works on this principle. Our device has a high time resolution and covers typically encountered ambient concentration ranges. It can measure very low particle concentrations of a few hundred particles per cubic centimeter even for ultrafine particles (i.e., two to three orders of magnitude more sensitive than rival technologies), while the upper detection limit is 1 million particles/cm(3), which hardly ever occurs in ambient settings. While other methods measure a fixed quantity, the response of our device can be tuned to be proportional to the particle diameter to the power of x, with at least 0.3 <or= x <or= 1.35. This opens up the possibility of giving more weight to smaller particles, which is a key feature, since on a per-mass basis, smaller solid particles have been shown to be more toxic than larger ones.