The sun sets next to a smokestack from a coal-burning power station in Beijing, January 9, 2008. Even breathing in a little ozone at levels found in many areas is likely to kill some people prematurely, the National Research Council reported on Tuesday. (David Gray/Reuters)

WASHINGTON (Reuters) -
Even breathing in a little ozone at
levels found in many areas is likely to kill some people
prematurely, the National Research Council reported on Tuesday.

The report recommends that the Environmental Protection
Agency consider ozone-related mortality in any future ozone
standards, and said local health authorities should keep this
in mind when advising people to stay indoors on polluted days.

“What impressed me was the consistency of the findings that
ozone clearly … does have an effect,” Dr. Evelyn Talbott of
the University of Pittsburgh, who worked on the study, said in
a telephone interview.

“It's small, but when you talk about a small effect over
300 million people, it's a lot.”

The report looks at ground-level ozone, a component of
smog, as opposed to the ozone found in the high atmosphere,
which protects the Earth from ultraviolet rays.

Ozone is a form of oxygen formed by the reaction of
sunlight on air containing other pollutants such as
hydrocarbons and nitrogen oxide. It is a powerful oxidizer,
meaning it can damage cells in a process akin to rusting.

It is known to cause respiratory problems and worsen heart
disease. Children and the elderly are at special risk.

The EPA asked the National Research Council, part of the
advisory National Academies of Science, to analyze the link
between ozone and early death.

ILL AT GREATER RISK

A committee appointed by the council found that deaths
related to ozone exposure are more likely among people with
pre-existing diseases and other factors that could increase
their susceptibility. But they said premature deaths are not
limited to people who are already within a few days of dying.

They looked at studies that linked deaths directly with
variations in ozone levels, as well as animal studies that
examined whether there was a biological explanation for ozone
causing death.

“Do you see the disease on days when ozone is higher? And
the answer is yes,” Talbott said. “There does appear to be a
dose response.”

The committee looked at studies done in several cities
across the United States as well as in Canada and Europe. They
took into account differences in temperature and humidity that
may affect the ozone level.

The effects on deaths are clear, Talbott said — and the
findings excluded serious illnesses and visits to the emergency
room if the patient did not die.

“If you have a town that has got many old people … then
obviously this ozone thing is probably a bigger player,”
Talbott said. “It touches everybody but I think it touches the
infirm and elderly (more).”

The EPA toughened standards for ozone pollution in March
but outside experts complained its new requirements were more
lax than the EPA's own scientists recommended.

The new standards are 75 parts per billion in ambient air
in the United States. The previous standard was 80 parts per
billion.

The EPA's Clean Air Scientific Advisory Committee
recommended a standard of 60 to 70 parts per billion.

(Editing by Will Dunham and Eric Walsh.)