A Shelter to Protect a Passive Sampler for Coarse Particulate Matter, PM10 - 2.5
This work designed and tested a shelter to protect a passive sampler for measuring coarse particulate matter, PM10 - 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 PM10 - 2.5 measured with the passive samplers to that measured with a filter-based dichotomous sampler. For most shelters, the PM10 - 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 PM10 - 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 PM10 - 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 PM10 - 2.5 ratio was 1.29. The linear relationship between PM10 - 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 PM10 - 2.5 without on-site measurement of wind speed.
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Document Type: Research Article
Affiliations: Department of Occupational and Environmental Health, University of Iowa, Iowa City, Iowa, USA
Publication date: 2008-04-01