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Joel Schwartz |
| Senior Fellow, Reason Public Policy
Institute |
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Clear Skies, Hazy Logic
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| By Joel
Schwartz |
04/23/2003
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| The Bush administration
contends coal-fired power plants kill tens of thousands of Americans
each year. The administration claims its Clear Skies Initiative,
which would cut power plant emissions by about 70 percent, will
reduce this toll by 12,000 per year and eliminate 370,000 asthma
attacks, conferring more than $90 billion worth of health benefits
on the American public. Environmental groups counter that Clear
Skies will kill tens of thousands by not reducing emissions faster
and further. All of these claims are false. Clear Skies will raise
electricity prices while providing few or no health benefits to the
breathing public. Even more draconian approaches, like Sen.
Jeffords's (I-VT) "Clean Power Act" would be an even worse deal for
American consumers.
Coal plants produce much of the
electricity in the eastern half of the United States. Unfortunately,
they also produce much of the east's air pollution - about
one-fourth of nitrogen oxides (NOx) and two-thirds of sulfur dioxide
(SO2), as well as one-third of national mercury emissions. NOx helps
form ozone smog, and some SO2 gets converted into sulfate particles,
contributing about 25 to 40 percent of fine particulate matter
(PM2.5) across the eastern U.S. Burning coal also releases mercury,
which environmentalists and regulators have blamed for high mercury
levels in some freshwater fish.
Clear Skies is intended to
reduce ozone smog by reducing power plant NOx emissions by 60
percent in 2008, and 67 percent in 2018. But EPA's NOx "SIP call"
regulation already requires a 60 percent reduction in power plant
NOx from May to September - the "ozone season" - starting in 2004.
Clear Skies would just extend those reductions to the colder months
of the year, when they would do little or nothing to improve human
health. Yet according the federal Energy Information Administration
(EIA), these additional NOx reductions would cost a few billion
dollars per year.
All of the mortality benefits and more
than 90 percent of the monetary benefits claimed for Clear Skies
come from reductions in PM2.5. Yet the claim that PM at current
levels is causing increased mortality is implausible. EPA based its
benefit estimate, as well as its stringent new PM2.5 health
standard, on the American Cancer Society (ACS) study of PM and
mortality.
The ACS study reported that a 10 microgram per
cubic meter increase in PM2.5 was associated with a four percent
increase in the risk of death during the 16-year study period. But
some odd features of the study suggest that PM is unlikely to be
responsible. According to the ACS results, PM increased mortality in
men, but not women; in those with no more than a high school degree,
but not those with at least some college; in former-smokers, but not
current- or never-smokers; and in those who said they were
moderately active, but not the very active or the sedentary.
These odd variations in the relationship between PM2.5 and
mortality seem biologically implausible. Even more surprising, the
ACS study reported that higher PM2.5 levels were not
associated with an increased risk of mortality due to respiratory
disease; a surprising finding, given that PM would be expected to
exert its effects through the respiratory system.
EPA also
ignored the results of another epidemiologic study that found no
effect of PM2.5 on mortality in veterans with high blood pressure,
even though this relatively unhealthy group should have been more
susceptible to the effects of air pollution than the general
population.
Sulfate PM - the type of PM caused by coal power
plant emissions - is a particularly implausible culprit. Ammonium
sulfate, the main form of sulfate PM, is used as an inactive control
in human studies assessing the health effects of inhaling acidic
aerosols. Inhaled magnesium sulfate is used therapeutically to
reduce airway constriction in asthmatics. Sulfate is also
naturally present in bodily fluids at levels many times the amount
that could be inhaled from air pollution. These factors suggest
sulfate PM shouldn't be expected to have detrimental effects on
health.
Mercury on Earth
Clear Skies would
reduce mercury emissions by 70 percent, at a cost of about $4
billion per year. Most mercury exposure is believed to result from
eating non-commercial freshwater fish from contaminated lakes and
rivers, but the mercury ultimately comes from air emissions.
Bacteria convert some of the mercury to methylmercury, which is the
form that can concentrate in animals. A recent study by the Centers
for Disease Control reported that eight percent of women of
childbearing age have blood mercury levels greater than EPA's
"reference dose" - a safety limit set at one-tenth the level
believed to cause subtle neurological impairment in children.
No one knows whether current mercury levels in fish are
caused by current U.S. mercury emissions. In its "Mercury Report to
Congress," EPA concluded, "it is not possible to quantify the
contribution of U.S. anthropogenic emissions relative to other
sources of mercury, including natural sources and re-emissions from
the global pool, on methylmercury levels in seafood and freshwater
fish consumed by the U.S. population. Consequently, the U.S. EPA is
unable to predict at this time how much, and over what time period,
methylmercury concentrations in fish would decline as a result of
actions to control U.S. anthropogenic emissions."
Given the
uncertainties, it's quite possible we could spend $4 billion per
year reducing mercury and end up with nothing to show for it but
higher electricity bills. Fortunately, there's a less expensive and
more certain way to reduce fish mercury levels. Methylmercury is
produced more rapidly in lakes that are more acidic, and sulfate
increases lakes' acidity. In recent field experiments, scientists
have shown that reducing sulfate in lakes reduces mercury in fish by
about the same amount as reducing mercury levels in the lake. Thus,
with sulfate reductions, the uncertainty in whether current fish
mercury levels are due to current U.S. mercury emissions,
transported emissions from other regions, or accumulated past
emissions is irrelevant. Sulfate reductions will reduce mercury in
fish regardless of where the mercury comes from.
EIA
estimated a 75 percent reduction in coal plant SO2 would cost about
$1.4 billion per year, and that the measures necessary to control
SO2 would reduce mercury emissions by 25 percent as well. And
although sulfate PM likely isn't harming human health, reducing SO2
emissions would have the aesthetic benefit of improving visibility
in eastern national parks.
The Bush administration should
abandon the NOx and mercury portions of Clear Skies and focus on SO2
reductions. The result would be lower mercury levels in fish,
greater visibility in national parks, and at least the potential for
net benefits in human welfare. In its current form, the only thing
clear about Clear Skies is that it's a bad deal for the American
public.
Joel Schwartz is the author of the forthcoming
policy studies "Understanding Air Pollution: Trends Health Effects
and Current Issues"(Cato), "Particulate Air Pollution: Weighing the
Risks" (CEI), and "No Way Back: Why Air Pollution Will Continue to
Decline" (AEI)
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