A Shelter to Protect a Passive Sampler for Coarse Particulate Matter, PM_{10 − 2.5}

Abstract

This work designed and tested a shelter to protect a passive sampler for measuring coarse particulate matter, PM _{10 − 2.5} . The shelter protects the sampler from precipitation and reduces the effects of wind on the deposition of particles to its collection surface. Six shelters were tested in a wind tunnel at three wind speeds: 2, 8, and 24 km hr ⁻¹ . Shelter performance was expressed as the ratio of PM _{10 − 2.5} measured with the passive samplers to that measured with a filter-based dichotomous sampler. For most shelters, the PM _{10 − 2.5} ratio averaged across wind speeds was well above one (2.4 to 8.5) and was generally dependent on wind speed. However, the PM _{10 − 2.5} ratio for one shelter, the Flat Plates shelter, was 1.04 with substantially less effect on particle deposition from wind speed. Eight week-long field tests were conducted to compare PM _{10 − 2.5} measured with a passive sampler installed in a Flat Plates shelter to that measured with a collocated filter-based dichotomous sampler. In these tests, the mean PM _{10 − 2.5} ratio was 1.29. The linear relationship between PM _{10 − 2.5} measured passively to that measured with the filter-based sampler had a Pearson correlation coefficient of 0.97 and was not significantly affected by the addition of weekly mean wind speed (p = 0.35). Although temperature was significant in this regression model (p = 0.02), it only improved the relationship marginally. The passive sampler in a Flat Plates shelter offers an inexpensive means to assess ambient PM _{10 − 2.5} without on-site measurement of wind speed.

Acknowledgments

The authors greatly appreciate the financial support from the Center for Health Effects of Environmental Contamination (University of Iowa) and the US Environmental Protection Agency (PR-RT-06-01007/U2C694).

Notes

**value is significantly different from 0 at α = 0.05 significance level.