March 14, 2008 — In an ongoing effort to understand the health implications of air quality, Constantinos Sioutas, professor of civil and environmental engineering in the USC Viterbi School’s Sonny Astani Department, has begun a new $1.12 million study to examine coarse particle pollution in rural, coastal and heavily populated inner city areas of the Los Angeles Basin.
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Constantinos Sioutas
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The new three-and-one-half year investigation, funded by the U.S. Environmental Protection Agency (EPA), will allow Sioutas to set up mobile air pollution monitors in a wide range of environmental niches around Los Angeles and neighboring counties, all of which are impacted differently by coarse particle pollution. Coarse particulate matter (PM) is larger in diameter than the ultrafine particle matter that Sioutas has been studying recently. Coarse PM is classified by the EPA as having diameters of between 2.5 and 10 micrometers, the larger of that range being roughly one-sixth the diameter of a human hair.
“We are seeing a lot of new epidemiological and toxicological evidence, especially among children, suggesting that coarse particulate matter, as well as ultrafine particulate matter – which is smaller than 0.1 micrometers in diameter -- is contributing to respiratory ailments such as coughing, asthma, decreased lung function and chronic bronchitis,” said Sioutas, who is holder of the Fred Champion Professorship in Civil and Environmental Engineering, and co-director of the Southern California Particle Center (SCPC), a leading center in the nation for the study of the nature and health effects of airborne particulate pollution.
“The goal of this study will be to assess the toxicity of coarse particle pollution in areas of the Los Angeles Basin that haven’t been studied before, for instance near inner city schools with minority populations, and compare those measurements to other urban and rural areas of the basin that have been overlooked,” he said.
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Bangwoo Han, a post-doctoral researcher in Sioutas' lab, designed the particle concentrator he is holding, one of two monitors being used in the study.
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Sources of Coarse Particulate Matter
Coarse particulate matter comes from both direct , or primary, and indirect, or secondary, sources. Primary sources include dust from paved and unpaved roads, industrial materials, brake linings, tire residues, trace metals and bioaerosols, such as pollen. Secondary particulate matter can be formed through complex reactions in the atmosphere when, for example, gas-phase byproducts of combustion, such as hydrocarbons, ammonia, sulfur dioxide and nitrogen oxides from automobiles, power plants and industries mix together with sunlight.
“Many adverse health effects of coarse particle pollution seem to be induced by oxidative damage in cells, which weakens the body’s ability to produce antioxidants and maintain a healthy metabolism,” Sioutas said. “The effects still aren’t completely understood, but some of the newest studies suggest that these larger, coarser particles of pollution can cause inflammation in the nose, lungs and cardiovascular system.”
Studies have shown that reduced lung function makes it harder for people to fight off infections and cope with allergens, as well as to extract needed oxygen from each breath.
State-of-the-Art Facilities
The EPA-funded study utilizes state-of-the-art facilities at the USC Aerosol Lab, which features the latest instrumentation and sampling equipment for sample collection. Colleagues at USC’s Keck School of Medicine and at the UCLA Geffen School of Medicine will assist with some of the sample analysis, under the direction of UCLA immunologist and co-SCPC Director Professor Andre Nel. Scientists under the direction of Jamie Schauer at the University of Wisconsin, Madison, will also collaborate. As the study progresses, exposure and toxicology data from the multi-institutional study will be combined with other major efforts currently under way in Southern California — at the SCPC and in the Multi-Ethnic Study of Atherosclerosis Air Pollution Study (MESA Air Study).
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Sioutas' patented monitor.
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Ten locations were chosen for the study to represent areas of the Los Angeles Basin affected by different PM sources. Seven of the 10 sites are currently used by the MESA Air Study investigators, who are cooperating with the study. The sites are varied and include two schools with large enrollments of Hispanic children in heavily polluted areas of south-central and eastern Los Angeles; a classic desert site in Lancaster; and several “near-freeway” sites in West Los Angeles, metropolitan/greater Los Angeles, and parts of rural Riverside County.
Sioutas and his co-investigators will use USC personal cascade impactors and coarse particle concentrators, developed through Sioutas’ Southern California Supersite Program, to collect the air samples. The impactors and the coarse particle concentrators are small, compact and inexpensive, and are being combined into a single, easily transportable package for the study.
Weekly and Seasonal Measurements
Over an 18-month period, samples will be collected during one 24-hour cycle each week from each of the sites, thus allowing researchers to sample coarse PM concurrently from midnight to midnight on specific days. These measurements will be coordinated with the regulatory sampling performed by both the South Coast Air Quality Management District and the Antelope Valley Air Quality Management District to take advantage of their PM data collection.
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Graduate environmental engineering student Vishal Verma adjusts an instrument at the mobile air analysis lab, run by Sioutas.
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The researchers will also conduct intensive winter (January) and summer (August) campaigns in three of the sites — L.A., Rubidoux (in Riverside County) and Lancaster — with multiple samples collected over the 24-hour period in order to determine the role of different sources in each region. In addition to the outdoor samples, researchers will measure particle pollution inside the classrooms of school sites in Long Beach and East Los Angeles to investigate what fraction of particles is entering the buildings.
Sioutas, who is interested in the impact of particulate matter on health, says the new data will augment recent findings from SCPC that children living near major interstate highways, including the 110, 710 and 405 freeways, are at high risk of developing asthma and other respiratory ailments due to the toxicity of airborne particulate matter.
Identifying the Culprits
“Identifying the primary culprits of coarse particulate pollution in these newly monitored areas will help us determine how toxic these particles really are,” he said, “and go a long way toward supporting EPA’s efforts to institute a national monitoring network for the coarser particle pollution.”
But solving the problem won’t be easy, he added. And whatever improvements may be made in cleaning up the air — by reducing the particulate matter emission rates of individual vehicles and trucks — could be outperformed by the increase in population, as well as the increase in commuters’ average drive times to-and-from work each day.
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Sioutas and post-doctoral researcher Zhi Ning review the monitor design.
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“We’re really at a standstill right now in our ability to reduce air pollution, so we should be looking at something entirely different,” said Sioutas, who is a member of the Air Quality Advisory Committee on PM for the state of California. “Of course the high price of gasoline has already made consumers think more seriously about buying hybrid vehicles, but more importantly, this region really needs to take a serious look at improving its system of public transportation.
“We already have efficient public transportation systems in large cities such as New York, London, Tokyo, Moscow and Paris, where people just don’t drive anymore,” he said. “That has drastically reduced vehicle-induced pollution and increased the quality of life, and that’s what our ultimate goal should be.”
