We have used the stationary air samplers for one week, up to several months. The sampler works by telling you the average air quality over the sampling period, so you can choose the time period that helps you best answer your question.
The sampling box is designed to keep rain and dirt away from the sampler, but rain and water will not wash away the chemicals. The chemicals are actually bound inside the sampling material, not sitting on the surface.
No! Although we have heard that sheep like to rub up against the sampling box.
We work with a machinist to create these boxes. They are built to withstand inclement weather, and to last for years. These sampling boxes can be purchased through EPREP. You also have the choice of creating your own box (see instructions). This is a more cost-effective option and gives you the choice of designing it to fit your specific research needs.