Study Links Fine PM With Respiratory, Cardiovascular Diseases; EPA's Proposed PM Standards Criticized
As environmental and health advocates, along with state officials and others, criticized EPA's proposed standards for particulate matter (PM), a study published in the March 8 Journal of the American Medical Association (JAMA) found that short-term exposure to fine PM increased hospital admissions for cardiovascular and respiratory disease among Medicare participants.
The study, of 204 U.S. urban counties, was conducted by researchers at the Johns Hopkins Bloomberg School of Public Health and Yale University's School of Forestry & Environmental Studies. The study authors stated they have created a reproducible approach for tracking the health risks of air pollution nationwide.
"By linking geographical locations and the health information of roughly all Medicare enrollees to the national air pollution and weather monitoring network, and to the U.S. census data, we can now routinely estimate health effects of air pollution nationally and regionally," said the study's lead author, Francesca Dominici, PhD, associate professor in the Department of Biostatistics at the Bloomberg School of Public Health.
The researchers analyzed data from a national database for 1999 through 2002 on hospital admission rates (constructed from the Medicare National Claims History Files) for cardiovascular and respiratory outcomes and injuries for 11.5 million Medicare enrollees (aged 65 years or older) who lived in the 204 U.S. urban counties (population greater than 200,000). The individuals lived an average of 5.9 miles from a PM 2.5 monitor.
The researchers found there was a short-term increase in hospital admission rates associated with exposure to PM 2.5 (PM less than 2.5 micrometers in diameter) for all of the health outcomes except injuries.
The largest association was for heart failure, which had a 1.28 percent increase in risk per 10 micrograms per cubic meter (µg/m3) increase in same-day PM 2.5. Cardiovascular risks tended to be higher in counties located in the Eastern region of the United States, which included the Northeast, the Southeast, the Midwest and the South.
"In the lung, particulate matter may promote inflammation and thereby exacerbate underlying lung disease and reduce the efficacy of lung-defense mechanisms. Cardiovascular effects may reflect neurogenic (arising in or stimulated by nerve tissues) and inflammatory processes," the authors write.
"Our findings indicate an ongoing threat to the health of the elderly population from airborne particles and provide a rationale for setting a PM 2.5 National Ambient Air Quality Standard (NAAQS) that is as protective of their health as possible," the researchers write. "The sources of particles contributing to the observed risks need to be identified so that control strategies can be targeted efficiently."
The same day JAMA published the study, EPA held hearings in Chicago, Philadelphia and San Francisco to gather public comment on two proposed rules -- "National Ambient Air Quality Standards for Particulate Matter" and "Revisions to Ambient Air Monitoring Regulations." These proposals were published in the Federal Register on Jan. 17 (see http://www.epa.gov/fedrgstr/EPA-AIR/2006/January/Day-17/a177.htm and http://www.epa.gov/fedrgstr/EPA-AIR/2006/January/Day-17/a179.htm respectively for notices on the proposals).
The American Lung Association argued that the proposed standards are weaker than those recommended by the agency's own staff scientists and other experts.
"More than 2,000 scientific studies have shown that the current particle pollution standards do not protect public health. EPA set those standards in 1997 when we knew much less than we do now about the health impact of particle pollution. We now know better. There is no excuse to set the new standards at levels that still do not meet the basic legal requirement outlined in the Clean Air Act, to protect the lives and health of the public," said John Balmes, MD, volunteer chair of the American Lung Association of California's Clean Air Technical Advisory Group.
Ten-year-old American Lung Association spokesperson Jonah Ramirez stated, "At age seven, I developed asthma. I wasn't born with it. I developed it. Why? Because I love to play outside. You see, I wasn't aware of the consequences of playing outside. While I was carelessly running around, laughing, playing, yelling, skating, being silly, I was also breathing deeply. Breathing dirty, smoggy air that my government claims is 'safe.' If this air is so safe, then why did it make me sick?"
Jim Cox, legislative counsel for Earthjustice, told the Philadelphia hearing, "EPA's proposed standards for particulate matter defy the Clean Air Act's mandate to protect public health with an adequate margin of safety. The proposed standards are less protective than recommended by the Clean Air Science Advisory Committee, and if promulgated, would allow thousands of needless deaths, asthma attacks, and hospital visits. Moreover, in failing to propose more protective secondary air quality standards, EPA would be violating legal requirements to protect important public welfare values like visibility and ecosystem health."
Industry groups like the American Chemistry Council (ACC) also testified in opposition to EPA's plans, but stated the proposal revisions would increase the stringency of the PM 2.5 NAAQS at a time when EPA should allow states to fully focus on attaining the current standards before requiring states to plan for a different target with different deadlines.
ACC Senior Director of Regulatory Affairs Ted Cromwell stated, "EPA hasn't determined what, if any, of the PM 2.5 constituents should be targeted. In the face of this uncertainty, it would be premature to change the standard."
According to ACC, EPA's proposal will further increase the demands on the nation's already burdened energy supply. The nation's natural gas bill was more than $200 billion, last year while in 1999 it was just more than $50 billion. While new rules may be intended to be "fuel neutral," the regulatory incentives appear to favor the operation of natural gas-fired units while discouraging use of other fuel sources, the group argued.
ACC President & CEO Jack N. Gerard said, "Air quality today is good and significantly improving even as the U.S. economy has grown."
Also present at the hearings were officials from the Edison Electric Institute (EEI), who argued that the rationale behind the agency's decision was shaky at best, particularly in light of the fact that major additional emissions cuts already are underway.
"Huge additional emissions cuts -- ordered just within the past year -- already are in the pipeline," said John Kinsman, EEI's director of air quality programs, speaking in San Francisco. "EPA should give current regulations a chance to work before seeking additional emissions reductions."
EPA's standards should be based on a complete and thorough review of the current scientific literature, which in this case was lacking, EEI said.
"Simply stated, EPA staff has cherry-picked the science, overemphasizing certain epidemiological studies that claim an association between fine particles and health effects, while giving short shrift to those that suggest they present little or no concern," said Steve Lomax, EEI's manager of air quality programs, in Philadelphia.
According to EEI, EPA's review of the scientific literature fails to assess and identify specific types of particulates or other pollutants that may be present in the air along with fine particulate matter, but which may be more significantly associated with health concerns. This shortcoming has been raised by the National Academy of Sciences and EPA's own Office of Inspector General, according to EEI. In fact, EPA does not know which of the many substances that comprise fine particulate matter might be causing a problem.
EEI also noted the far-reaching and severe consequences of being designated a "non-attainment" area. A non-attainment status discourages new industry from locating within such areas and may prevent existing industries from expanding, both with significant impacts on jobs and local economies, EEI argued.
Additional information on PM 2.5 can be found at http://www.epa.gov/wtc/pm25/pm_fact_sheet.html.
Johns Hopkins Bloomberg School of Public Health: http://www.jhsph.edu
Department of Biostatistics: http://www.biostat.jhsph.edu
Francesca Dominici: http://faculty.jhsph.edu/?F=Francesca&L=Dominici
Yale's School of Forestry & Environmental Studies: http://www.yale.edu/forestry
This article originally appeared in the 03/01/2006 issue of Environmental Protection.