Dm. Ono et al., Systematic biases in measured PM10 values with US Environmental ProtectionAgency-approved samplers at Owens Lake, California, J AIR WASTE, 50(7), 2000, pp. 1144-1156
Citations number
24
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
From 1993 through 1998, Wedding or Graseby high-volume PM2.5 samplers were
collocated with tapered element oscillating microbalance (TEOM) samplers at
three sites at Owens Lake, CA. The study area is heavily impacted by windb
lown dust from the dry Owens Lake bed, which was exposed as a result of wat
er diversions to the city of Los Angeles. A dichotomous (dichot) sampler an
d three collocated Partisol samplers were added in 1995 and 1999, respectiv
ely. U.S. Environmental Protection Agency (EPA) operating procedures were f
ollowed for all samplers, except for a Wedding sampler that was not cleaned
for the purpose of this study. On average, the TEOM and Partisol samplers
agreed to within 6%, and the dichot, Graseby, and Wedding samplers measured
lower PM10 concentrations by about 10, 25, and 35%, respectively. Surprisi
ngly, the "clean" Wedding sampler consistently measured the same concentrat
ion as the ''dirty" Wedding sampler through 85 runs without cleaning. The f
inding that the Graseby and Wedding high-volume PM10 samplers read consiste
ntly lower than the TEOM, Partisol, and dichot samplers at Owens Lake is co
nsistent with PM10 sampler comparisons done in other fugitive dust areas, a
nd with wind tunnel tests showing that sampler cut points can be significan
tly lower than 10 mu m under certain conditions. However, these results are
opposite of the bias found for TEOM samplers in areas that have significan
t amounts of volatile particles, where the TEOM reads low due to the vapori
zation of particles on the TEOM's heated filter. Coarse particles like fugi
tive dust are relatively unaffected by the filter temperature. This study s
hows that in the absence of volatile particles and in the presence of fugit
ive dust, a different systematic bias of up to 35% exists between samplers
using dichot inlets and high-volume samplers, which may cause the Graseby a
nd Wedding PM10 samplers to undermeasure PM10 by up to 35% when the PM10 is
predominantly from coarse particulate sources.