Short-term exposure to current levels of ozone pollution is directly linked to poor health in humans and premature deaths, a new National Research Council report concluded on Tuesday.

Ozone is a form of oxygen, which acts as a shield against harmful ultraviolet rays from the Sun, if it is high in the atmosphere. If it is on the ground level, ozone can cause lung damage, trigger asthma attacks and worsen heart disease. Children and elderly are at high risk.

The report looked on the ground-level ozone and found that it “does have an effect. It’s small, but when you talk about a small effect over 300 million people, it’s a lot,” Dr. Evelyn Talbott of the University of Pittsburgh, who worked on the study, said in a telephone interview with Reuters.

"Based on a review of recent research, the committee found that deaths related to ozone exposure are more likely among individuals with pre-existing diseases and other factors that could increase their susceptibility. However, premature deaths are not limited to people who are already within a few days of dying," a statement from the panel said.

The panel also added that that "studies have yielded strong evidence that short-term exposure to ozone can exacerbate lung conditions, causing illness and hospitalization and can potentially lead to death."

The news is not new as environmentalists and health advocates have long argued that a string of health studies and surveys show that exposure to smoggy air not only aggravates respiratory problems, but causes thousands of deaths a year.

Previous studies, done in several cities across the U.S. as well as in Canada and Europe, linked deaths directly with variations in ozone levels. There were also 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. There does appear to be a dose response. If you have a town that has got many old people…then obviously this ozone thing is probably a bigger player. It touches everybody but I think it touches the infirm and elderly (more),” Talbott said.

The Environmental Protection Agency (the sponsor of the recent research) was highly criticized last month when it issued new federal smog standards that were tighter than previous standards but did not follow the recommendation of its own scientific advisory committee, which had concluded even stricter standards were needed to protect human health.

The EPA's Clean Air Scientific Advisory Committee recommended setting the standard at 60 and 70 parts per billion, but EPA adopted a 75 parts per billion standard, reducing it from 80 parts per billion. According to environmental and government watch-dog groups, the White House officials intervened to prevent the EPA from setting stronger standards that would have been more costly for industry.

However, the authors of the Tuesday report added that for a better understanding of all the possible connections between ozone and mortality, further research should address whether exposure for more than 24 hours and long-term exposure, weeks to years, are associated with mortality, including how ozone exposure could impact life expectancy.

Also, more research could look at how other pollutants, such as airborne particulate matter, may affect ozone and mortality risk.