The evidence is overwhelming: EPA Must Set a Much Stronger Ozone Air Quality Standard
On June 21, 2007 the U.S. Environmental Protection Agency
(EPA) proposed to strengthen the official “limit” on ground level ozone smog. Unfortunately, EPA’s
proposal fails to follow the law and protect public health
adequately from this widespread and dangerous air pollutant.
Overwhelming scientific evidence, including reviews by independent
scientists, confirm that public health is seriously at risk
and needs much more protection. EPA will take comments until
October 9, 2007, including at five public hearings on August
30 and September 5. The American Lung Association and many
other medical societies, public health and environmental
groups are urging EPA to adopt standards that provide much
What is ozone?
Ozone (O3), commonly known as smog, forms when hydrocarbon
vapors and nitrogen oxides react in the presence of sunlight
Nitrogen oxides are emitted from combustion sources such
as power plants, industrial boilers, motor vehicles, locomotives,
Hydrocarbon vapors are emitted from motor vehicles, small
engines, chemical plants, refineries, factories, gas stations,
paint and other sources.
Why is ozone harmful?
Ozone reacts chemically (“oxidizes”) with internal body tissues, such as those in the lung. Some have described it as a “sunburn” on
It acts as a powerful respiratory irritant at the levels
frequently found across the nation during the summer months.
Ozone exposure may lead to:
• premature death
• shortness of breath, chest pain, wheezing and coughing
• inflammation and damage to the lining of the lung
• increased asthma attacks, greater need for medical treatment
and for hospitalization for people with lung diseases, such
as asthma or chronic obstructive pulmonary disease (COPD)
• long-term, repeated exposure to high levels of ozone may
also lead to reduced lung capacity
Who are most at risk?
• people with lung disease, especially chronic lung diseases
such as asthma and COPD
• children, because their airways are smaller, their respiratory
defenses are not fully developed, and their higher breathing
rates increase their exposure
• people who work or exercise outdoors
• senior citizens
• otherwise healthy individuals who respond to lower levels
of exposure than the average person
What is the ozone standard?
• The Clean Air Act requires EPA to set and regularly review
air pollution limits, which are called National Ambient Air
Quality Standards (NAAQS). EPA must follow the latest scientific
evidence to set them where they protect public health, including
the health of sensitive populations, with an adequate margin
• The standards help inform the public when the air is unhealthy
and drive the clean up of air pollution.
• The last time the EPA revised the standard for ozone pollution
was 1997, when the agency set an 8-hour average standard
of 0.08 parts per million. The current standard is effectively
0.084 ppm due to a loophole that allows states to round down
• The Clean Air Act requires that the EPA set the standard to protect public health “with an adequate margin of safety” to
protect sensitive populations that respond at lower concentrations
than healthy adults. In 2002 the Supreme Court unanimously
ruled that protecting health was the only basis for the standard.
How is EPA proposing to change the ozone standard?
• Overwhelming evidence shows that the ozone standard must
be much stronger than EPA has proposed to protect public
health from serious harm.
• EPA has concluded that new scientific studies show that
the current standards fail to protect public health, particularly
for those with lung diseases, like asthma or emphysema.
• EPA has proposed to set the health standard to a level within the range of 0.070-0.075 ppm (70 -75 ppb) and to drop the rounding loophole. This is a modest improvement but it is weaker than EPA’s
science advisors have recommended.
• Importantly, EPA is considering keeping the current weak
standard of 0.084 ppm, a move that polluters are pushing.
EPA could set a final standard that does nothing.
What did EPA’s independent science
The Clean Air Scientific Advisory Committee (CASAC) is a
group of expert scientists appointed under the Clean Air
Act to advise the EPA Administrator on the review of the
NAAQS. After reviewing the 2,000-page summary of the scientific
research and extensive additional analysis by the EPA staff,
the 23 ozone scientists unanimously concluded:
• There is no scientific justification to keep the current
• The rounding loophole must be eliminated.
• The 8-hour ozone standard should be set in the range of
0.060 to 0.070 ppm.
• The ozone health standard must explicitly include the “margin of safety” required
by the Clean Air Act.
Why does the current standard need strengthening?
New epidemiological and clinical studies have shown that
breathing ozone can harm health at concentrations lower than
the current standard.
This has prompted not only the CASAC, but the World Health
Organization, the American Academy of Pediatrics, the State
of California, EPA’s Children’s Health Protection Advisory
Committee, the American Medical Association and others to
recommend much stricter ozone standards.
• Clinical studies of healthy adults show decreased lung
function, increased respiratory symptoms, inflammation, and
increased susceptibility to respiratory infection at the
current standard of 0.08 ppm, with some studies showing adverse
lung function effects and symptoms at 0.06 ppm.
• Breathing ozone can kill. Short-term increases in ozone
were found to increase deaths from cardiovascular and respiratory
causes in a large 14-year study in 95 U.S. cities.
• The relationship between mortality and ozone was evident
even on days when pollution levels were below concentrations
of 0.06 ppm.
• Due to a loophole, communities can round down their measurements and still meet the ozone standard. This means that some large metropolitan areas don’t
have to clean up their air. Newer monitoring technology has
eliminated the original reason for this practice.
What is the timetable for EPA action?
• August 30, 2007 -- public hearings in Philadelphia and
• September 5, 2007 -- public hearings in Atlanta, Chicago
• October 9, 2007 -- deadline for written comments
• March 12, 2008 -- EPA announces final standards
What does the American Lung Association
recommend that EPA do?
• The existing standard fails to protect public health, so
EPA must strengthen it.
• EPA should set an 8-hour primary standard for ozone of
0.060 ppm to protect public health with a margin of safety.
• EPA must eliminate the rounding loophole.