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Research Contributions
EPA's Clean Air Research Program in EPA's Office of Research and Development is providing the science needed to support regulatory decision making for air pollutants. Research contributions include:
Near Roadway Research Linking Source to Health Effects
A series of near roadway studies on air pollutants from motor vehicles is advancing understanding of the health risks to those living or working near highways and other urban roads. Scientists are investigating the concentration profiles of air pollutants around roads resulting from both vehicle exhaust and road wear. Important questions are being addressed including: How do these concentrations disperse with distance from the road and how can air pollutants be mitigated, especially in the vicinity of schools.
Initial findings show that dispersal of pollutants away from the roadway varies by the topography around the road and the characteristics of the pollutant itself. These data are being used to help refine and improve models to predict the public's potential exposure. Studies to assess health effects from vehicle emissions in areas near major urban roadways are also under way. The science will provide important information to determine the effectiveness of mobile source regulations and future actions to protect public health.
Research Links PM to Disease
Numerous studies by EPA and others have shown that short-term exposure to particulate matter (PM) can adversely affect human health. Generally, exposure to PM is associated with illness and premature death independent of the effects of other gaseous pollutants in the atmosphere. Not everyone is equally susceptible. The very young, the genetically predisposed, the elderly, and those with pre-existing heart or lung disease are now known to be predisposed to the adverse health effects of PM. Striking findings also suggest that extended PM exposure can lead to chronic lung and cardiovascular disease and/or a shortened life span. These studies have advanced the science for future reviews of the PM standards.
More information on health effects from particulate matter
Study Finds PM Moves Indoors
EPA scientists have found that PM2.5, the component of PM smaller than 2.5 micrometers in diameter, penetrates easily into most indoor environments where people spend much of their time. While the strength of the correlation can vary by season and location, it appears that outdoor PM2.5 levels reasonably represent personal exposure to PM2.5. Exposure studies have shown that background levels of other gaseous pollutants, such as ozone and nitrogen dioxide, can be surrogate indicators for personal PM2.5 exposure. These studies have advanced the science for future reviews of the PM standards.
More information on particualte matter research
Research Shows PM's Effects on Lung Disease
New findings by EPA and others demonstrate that PM2.5 deposits in critical regions of the lung after it enters the respiratory tract. Some parts of a diseased lung collect eight to10 times more particles than a healthy lung, a fact that has major health implications for people with lung disease. This work suggests that people with lung disease may be more affected by increasing levels of PM2.5 because they receive greater doses. These studies have advanced the science for future reviews of the PM standards.
For more information:
Particulate matter, dosimetry, and fate
Particulate matter and susceptible subpopulations
Discoveries Indicate Possible Mechanisms for Disease
Scientists have developed multiple hypotheses to explain how the chemical and physical properties of PM could produce disease. Further, scientists can now experimentally investigate the mechanisms that enable very small concentrations of inhaled PM to cause changes in the heart and lung that lead to increased illness and death. The laboratory and field evidence does not implicate one specific toxic quality of PM to the exclusion of others. Qualities such as the size of the PM and presence of certain chemical components, such as metals, all appear to contribute to its toxicity. These studies have advanced the science for future reviews of the PM standards.
More information on particulate matter and mechanisms of injury
Models and Tools Developed to Implement PM Standards
Researchers have developed more advanced tools to measure and model fine particles. The models enable researchers to estimate how much potentially toxic PM will travel from a source to populations that can be affected and to predict how reductions in PM emissions can impact exposure miles away. These tools can be used by the EPA regions, states, and locals to meet PM standards. New, specialized measurement techniques should help scientists measure the particle size and composition of diverse kinds of PM and PM from unconventional sources.
For more information:
EPA Positive Matrix Factorization 1.1 (EPA PMF 1.1)
EPA Unmix 6.0 Model
PM Research Centers Provide Source-to-Health Effects Research
The Clean Air Research Program established five PM Research Centers at universities to compliment and enhance research by laboratories and centers in EPA's Office of Research and Development. These PM Centers focus on the links between sources of PM and their health effects. They are providing invaluable and novel research on the health impacts of PM, including basic mechanisms and information that relates to PM size and composition. A strength of the PM Centers is their scientific breath and flexibility as well as opportunistic application of their expertise applied to unique environments - e.g, Los Angeles. The PM Centers are central to providing important epidemiological research for the Clean Air Research Program that contributes to the development of regulatory risk assessments associated with PM and other air pollutants regulated by the EPA.
More information on Airborne Particulate Matter Research Centers