|Children at Risk|
Children are at special risk: they breathe 50 percent more air per pound of body weight than adults do.Because children's respiratory systems are still developing, they generally are more susceptible toenvironmental threats than healthy adults. Damage caused by air pollution can mean they never reach theirpotential lung development. Exposure to fine particles is associated with increased frequency ofchildhood illnesses, which are of concern both in the short run, and for the future development ofhealthy lungs in the affected children. Babies and young children are especially susceptible to fineparticles.
A recent study found a 26 percent increased risk for Sudden Infant Death Syndrome (SIDS) in cities withhigh levels of particulate pollution. Moreover, infants in high pollution areas were 40 percent more likely to die ofrespiratory causes.Particles are also associated with increased respiratory symptoms and reduced lung function inchildren, including symptoms such as aggravated coughing and difficulty or pain in breathing. These canresult in school absences and limitations in normal childhood activities.
Breathing fine particles aggravates asthma symptoms and while children make up 25 percent of thepopulation, they comprise 40 percent of all asthma cases. Asthmatic children whobreathe fine particles use more medication, receive more medical treatment, and visit the hospital moreoften.
The link between power plants and fine particles is clear. In most areas of the country, sulfate - acidicfine particles - dominate the total mass of fine particle pollution measured at monitors locatedthroughout the United States. And power plants outstrip all other polluters as the largest source ofsulfate air pollution in the U.S. In 1998, power plants were responsible for 67 percent-a full two thirds- of theannual total sulfur dioxide (SO2) and over a quarter of the nitrogenoxides (NOx) emitted in the U.S.; over 13 million tons ofSO2 and over six million tons of NOx.Sulfur dioxide and NOx gas emissions from power plants form fineparticles as they chemically convert in the atmos-phere to form fine sulfate and nitrate particles. Powerplants also emit fine carbon soot particles directly from their smokestacks, which may appear as a blackplume leaving the stack. In 1999, power plants directly emitted nearly 300,000 tons of fine carbon sootparticles.
While the 1990 Clean Air Act Acid Rain Program (Title IV) had resulted in significant initial progress inreducing SO2 emissions from power plants, those emissions have recentlybegun to rise. The National Emissions Trends Report shows that power plant SO2 emissions crept upward every year since 1995, rising more than 10 percent. Disturbingly, in 1998, powerplants emitted 1.26 million more tons of SO2 than they emitted in1995. Nitrogen oxideemissions from power plants have risen 44 percent since 1970. Moreover, power plantNOx, PM10, and volatile organicemissions-all of which contribute to fine particle levels - have also crept up slightly over the past fewyears according to the 1998 EPA report.20 Taken together, while these increases are not enormous, the data suggest poorprogress in curbing power plant emissions.
Indeed, the largest share of power plant-derived fine particle pollution comes not from direct emissionsbut instead from the conversion of SO2 and NOx into fine particle sulfate and nitrate.21 This impact is mostpronounced in the mid-western United States - an area densely populated with coal-burning power plants -and in the eastern United States - areas downwind of the vast majority of the nation's coal-burning powerplants.
Even before London's "killer fog" event, coal combustion was understood to be the principle source ofairborne soot and fine particles. Most of the coal used in the U.S. today is burned by power plants forthe production of electricity. Among power plants, the oldest coal-fired facilities produce the largestshare of the particle-related air pollution. Just over half of all power plant boilers in the U.S. arefueled by coal. However, coal-burning power plants account for nearly 90 percent of the SO2 emitted by all power plants.
Because of the now obvious associations between health, fine particles, and coal-fired electricgeneration, health researchers have recently made preliminary estimates of the relative contribution ofpower plants to total deaths. Using rudimentary analysis, researchers at the Harvard School of PublicHealth have estimated that power plants are responsible for approximately 15,000 deaths per year (i.e.,one-quarter of an assumed 60,000 fine particle related deaths per year). Indeed, embedded in EPA'sRegulatory Impact Analysis for the PM2.5 fine particle health standardwas the power sector's contribution to death and disease from particles in our air. Similarly, in EPA'scost-benefit analysis of the Clean Air Act, health benefits associated with reductions in powerplant-generated fine particle pollution provided strong justification for pollution control costs imposedby the Act. A recentHarvard School of Public Health study of two coal-fired power plants in Massachusetts found that the fineparticle pollution from these plants may be associated with over 100 deaths annually.
Despite steps underway to reduce power plant emissions, a major hurdle remains: to date, the vastmajority of coal- and oil-fired power plants have circumvented the most protective air emissionsstandards required of modern power plants. When the Clean Air Act was amended in 1970 and 1977, it wasassumed that many of the nation's older power plants would be retired and replaced by cleaner, new powerplants and therefore should be exempt from the emission regulations governing new plants. However, for avariety of reasons, these plants have not retired. Because of this "grandfathering" loophole, coal-firedpower plants are largely exempt from modern, state-of-the-art pollution control requirements. The vastmajority of these plants fail to meet modern pollution standards for SO2 and NOx. This special treatment for "grandfathered"power plants permits these facilities to pollute at rates up to 10 times that of modern coal plants.
Polluting coal-fired power plants must be made to comply with modern emission control standards. Inaddition, the nation's power fleet should be held to nationwide caps on all four of the key power plantpollutants, including nitrogen oxides, sulfur dioxide, mercury and carbon dioxide. Reducing power plantNOx and SO2 emissions by 75 percentfrom 1997 emissions levels will dramatically reduce fine particle pollution so we can all breathe easier.A 75 percent reduction is both necessary to protect our health, and is readily achievable. The death,hospitalizations and lost work time caused by fine particles from power plants can be reducedcomprehensively only when the Clean Air Act's 30-year loophole for old dirty power plants is finallyclosed.
Based on the Abt Associates analysis and the robust health evidence it is based on, reducing power plantsulfur dioxide and nitrogen oxide emissions by 75 percent will save 18,000 lives every year. Moreover,the technology for reducing these emissions exists today. There is no excuse for further delay.Protecting the health of our loved ones, both the old and the young, compels swift action to cutdramatically the death and disease visited upon Americans by these dirty, antiquated plants.
Federal legislation now pending would reduce particle-forming sulfur dioxide and nitrogen oxide emissionsby 75 percent from 1997 levels and significantly reduce mercury, and carbon dioxide emissions. Recently,the Environment and Public Works Committee of the U.S. Senate began hearings on the issue ofcomprehensive power plant cleanup. Given the uncertainty facing the industry from the combination offuture environmental requirements and the advent of electric industry deregulation, even some of thelargest polluting power companies have called for comprehensive legislation to clearly spell out theirair pollution reduction commitments into the foreseeable future. Clearly the time is ripe to save livesby cutting fine particle pollution from the electric power industry.
Health Research Links Fine Particles with Death and Disease
The health effects of fine particle soot have been suspected for centuries. Early records suggest thatKing Edward II of England in the 14th century, ordered people who fouled the air with coal smoke to betortured. In the steel town of Donora, Pennsylvania, in October 1948, the air became so filled withpollution that people could not see across the street. About half of the population of 14,000 in the townbecame sick, 10 percent severely ill, and 20 deaths were attributed to the episode. In London, four yearslater, a deadly fog blanketed the Thames River valley when a temperature inversion trapped air pollutionnear ground level from December 5th to 9th. The smoke from London's industries, residential furnaces andfireplaces filled the air. By the end of the episode, the death toll climbed to over three thousand; afive-fold increase over the normal death rate.
The political response to the London event was immediate and decisive - burning of soft coal was bannedin central London and smokestacks and chimney heights were raised, thus sending the pollution elsewhere.As would be repeated in the United States in the ensuing decades, "dilution" was seen as the "solution topollution." The assumption was that as the pollution dispersed over a wider area, the lower overallpollution levels would entail no adverse health effects.
In the early 1970's, U.S. researchers established a statistically significant "association" between airpollution at then-current levels and death rates in a number of U.S. cities. However, these studies couldnot establish a cause-and-effect relationship because they did not control for a variety of other variables that could have explained the relationship. For example, seasonal variations might be indicative of the amount of time people spend indoors or the spread of infectious diseases. The state of the science in 1980 did not establish a sufficiently robust link between air pollution and death, but it suggested that detailed investigations of this relationship would be critical to improvements in public health.
Since that time, there have been extensive animal and human tests on the health effects of breathing fineparticles. These tests show that fine particles can harm the respiratory tract and cause cardiac failureand therefore may be responsible for significant effects on health. But the conventional wisdomon air pollution's link to early death did not change until two landmark studies clearly established thelink between particles and death by tracking many individuals over long time periods in differentgeographic areas.
In a 1993 article in the New England Journal of Medicine, researchers reported on a study that trackedover 8,000 people in the United States over a period of seventeen years in six cities, each characterizedby a range of fine particle levels. After controlling for other factors (smoking status, body mass,occupational risks, etc.), they found the risk of death in highly polluted areas was 26 percent greaterthan in areas with the lowest pollution levels. The so-called Harvard "Six Cities" study also showed forthe first time that there is a "linear" or straight line statistical increase in risk directlyproportional to increased fine particle concentrations. This critical finding suggested that there is nosafe level of fine particles to breathe.
In March 1995, a second landmark study was published supporting the conclusions of the Six Cities study.The American Cancer Society (ACS) study tracked over half a million adults in 151 different metropolitanareas for more than seven years. Detailed information was collected from study participants regardingtheir age, sex, weight, height, demographic characteristics, smoking history, alcohol use, occupationalexposures, and other factors. The study found a 17 percent increase in mortality risk in areas withhigher concentrations of fine particles. The investigators also found linkages between fine particles andtotal mortality and with cardiopulmonary disease. The researchers concluded that exposures to currentlevels of air pollution are shortening the lives of Americans by several years.
In his book summarizing the body of evidence on fine particle health effects, Dr. John Spengler, Directorof the Environmental Science and Engineering Program of the Harvard School of Public Health, concludedthat the most obvious and direct interpretation of the data is that approximately four percent of thedeath rate in the U.S. can be attributed to air pollution. That figure is large (approximately 60,000deaths per year) and exceeds a hundred-fold the sum total of all deaths caused by the other pollutantsthat the U.S. EPA regulates.
Relying on these studies and others, in 1997 EPA issued new air quality standards for fine particles.Polluting industries immediately attacked the standards and the scientific studies underlying them as"junk science." Industry critics claimed the results were likely the product of flawed statisticalmethodology, due to poorly controlled exposure data, or poorly controlled factors such as heat orsmoking. Industry demanded the raw data be released to its paid consultants for reanalysis. However,because confidentiality and personal privacy were guaranteed to the study participants, the researcherscould not agree to the requests. Instead, the researchers agreed to a third-party reanalysis by theHealth Effects Institute, a non-profit organization, jointly funded by EPA and industry to be anindependent and unbiased source of information on the health effects of major pollutants.
HEI Reanalysis Confirms Landmark Studies
The Health Effects Institute (HEI) reanalysis of the Six Cities and ACS studies was performed in twoparts by Dr. Daniel Krewski of the University of Ottawa and Dr. Richard Burnett of Health Canada. The first phase involved anintensive audit of data quality combined with an independent effort to replicate the results of theoriginal studies using the same data and techniques. The second phase, released during the summer of2000, focused on extensive testing of the sensitivity of the original findings to a variety of differentstatistical techniques and 30 different variables that industry claimed would explain the differences inmortality between the cities such as other pollutants, climate, and socio-economic factors. However, thereanalysis found that these factors made relatively little difference in the results - including theeffects of temperature and smoking - with the exception of an association found between education leveland relative risk of death (lower education levels were associated with higher risk).
Most importantly, through its reanalysis HEI confirmed the conclusions of both studies. For the HarvardSix Cities Study, HEI found that the relative risk between Steubenville (most polluted) and Portage(least polluted) was 28 percent -two percent higher than the 26 percent in the original study. The HEIreanalysis of the ACS data found a relative risk of 14 percent higher in the most polluted city comparedto the cleanest - somewhat smaller than the 18 percent that the investigators found in the originalstudy. In its analysis for this study, Abt Associates employed the more conservative value from thereanalysis of the ACS study as the basis for the mortality estimates in the report. Thus, the reanalysisconfirmed the science behind EPA's new fine particle health standard and provided additional evidencelinking fine particles at current levels to serious adverse health effects. In short, the reanalysissystematically dispelled each of the arguments leveled against the original studies.
New Research Supports Association Between Particles and Death
About the same time, HEI also released the results of a completely new study of acute mortality (deathstracked daily with air pollution levels) in the 90 largest U.S. cities. In the study-the NationalMorbidity and Mortality Air Pollution Study (NMMAPS) - a team of investigators from Johns HopkinsUniversity and the Harvard School of Public Health examined increases in daily mortality andhospitalization rates caused by short-term rises in particulate matter levels in the air. The investigatorsdeveloped a new standardized methodology for examining pollution effects across many different U.S.cities including state-of-the-art statistical techniques to examine the effects of multiple pollutantsand the extent that lives are being shortened.
The National Morbidity and Mortality Study demonstrates the life shortening power of air pollution.Industry critics have long argued that the tens of thousands of deaths associated with particulate matterin these studies are, in their words, "insignificant." They claim the victims' lives are being shortenedby only a few days because they were already near death and the rise in air pollution simply provided thefatal "last straw." Scientists euphemistically labeled this notion "harvesting."
NMMAPS categorically demonstrates that theconcept of harvesting is incorrect. If the industry arguments were valid, then the death rate should fallbelow average as air pollution levels return to normal - following the "harvest" of frail individuals.But, in fact, just the opposite is true. Instead of a harvest, researchers observed that the death rateremains higher than normal for some time, lingering well beyond the time of the high air pollutionepisode and indicating that individuals weakened by the high air pollution levels continue to die forweeks or months following the air pollution event. Moreover, recent analyses of chronic (i.e., long-term) exposure support theconclusion that life expectancy in more polluted areas is reduced by several years.
Critics have also argued that other pollutants may be responsible for observed health effects andmortality attributed to fine particles. But, using new methods, NMMAPS and the reanalysis carefullyisolated the impacts of particulate matter. In fact, NMMAPS found strong evidencelinking daily increases in particle pollution to increases in death in the largest U.S. cities. Theassociation between PM10 (or particulate matter) and mortality persisted even when other pollutants were considered.
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