| It Saves MoneyIn the
This proposed method of determining concentrations emitted from agricultural
sources will most likely increase the cost of sampling. But, says Buser,
"By improving the samplers and sampling protocol used to regulate
agricultural businesses, we could save that sector of the economy a
lot of money in the long run, without any harm to air quality."
And though it will go a long way toward correcting errors associated
with particulate-matter sampling, it will not eliminate them. "I
don't think we're going to have a perfect sampler any time in the near
future," he says. "The technology just isn't there to eliminate
the two errors. And it's not for a lack of trying, because researchers
have been working on improving dust samplers for years. Developing a
sampler to accurately measure a pollutant as diverse as particulate
matter, with sizes varying from less than 1 µm to over 100 µm,
is extremely challenging.
"Results from the ambient samplers set up across the United States
to determine whether or not a region is in compliance with air quality
standards for PM10 and PM2.5 may be right on the money for urban dust
measurements under normal conditions," says Buser.
But if the region where a sampler is located is prone to dust storms
like the one seen in Lubbock on April 15, 2003, the sampler most likely
will greatly overestimate PM10 concentrations. A storm like that one
exposes samplers to dust particles that are mostly larger than 10 µm,
and these greatly increase the overall error associated with ambient
air samplers. Such dust storms could erroneously place a region in danger
of receiving a nonattainment classification for PM10 or PM2.5, or both.
"These sampler errors may proveand have proven in some instancesto
be extremely costly to agriculture," says Buser. "The agricultural
community has seen only a small fraction of the impact of future air
quality regulations likely to come. For instance, California legislators
are proposing a state bill (SB 700) that would establish a comprehensive
new definition of the term 'agricultural operations' and require farmers
to obtain and maintain an air pollution permit to perform them. Included
would be such common practices as disking, irrigation pumping, and harvesting.
"And, as we all know, once a bill like that is passed in one state,
other states tend to follow. Though most states currently require agricultural
processing operationssuch as cotton gins, feed mills, and grain
elevatorsto obtain and maintain operating permits, the requirement
has not yet been extended to individual farmers' tillage and harvesting
Compliance Is Key
While ARS has several researchers working in the wind erosion arena,
including at the Wind Erosion and Water Conservation Research Unit in
Lubbock, Buser is one of very few dealing with agricultural air quality
in terms of compliance.
According to Buser, "The difference between air quality compliance
research and wind erosion research can be seen in the goals of each.
The fundamental goal of most wind erosion research is to minimize or
eliminate soil loss by modifying agricultural practices. But the fundamental
goal of compliance research is to ensure that agricultural producers
and processors can obtain and maintain the operating permits required
to allow them to stay in business.
"Compliance-related research includes rigorous evaluationusing
sound scienceof regulations applied to agricultural industries
and development of abatement strategies and devices to help the agricultural
community comply with national air quality standards.
"In my opinion," Buser says, "both areas of research
are critical."By Don
Comis, Agricultural Research Service Information Staff.
This research is part of Air Quality, an ARS National Program (#203)
described on the World Wide Web at www.nps.ars.usda.gov.
Michael D. Buser is
in the USDA-ARS Cotton Production
and Processing Research Unit, Cropping Systems Research Laboratory,
Rte. 3, Box 215, Lubbock, TX 79401; phone (806) 746-5353, fax (806)
"A Bum Rap for Agricultural Dust?" was published in
the May 2004
issue of Agricultural Research magazine.