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Ozone Levels in PPB in the U.S.

Ozone consists of three oxygen atoms, known as a triatomic molecule, in a highly reactive state. This molecule exists naturally in the upper atmosphere and protects life on the planet from the radiation of the sun's rays. Even so, ozone levels in the lower atmosphere cause many respiratory problems, especially for those with asthma and preexisting respiratory diseases.

  1. Hazardous Level of Ozone

    • The U.S. Environmental Protection Agency (EPA) stated that levels of ozone over 100 part per billion (ppb) are dangerous to human health. The EPA further stated that levels approaching 100 ppb can irritate the respiratory passages and the eyes. The organization issues an "ozone warning" when levels reach 300 ppb and an "ozone emergency" when the level exceeds 350 ppb.

    Trends in Ozone Levels

    • An article appearing in the July 2010 issue of the "International Journal of Environmental Research and Public Health" investigated ozone levels in 19 urban communities throughout the Southeastern U.S. from 1987 to 2000, using data from the North American Regional Climate Change Assessment Program (NARCCAP). The authors analyzed this information and have predicted that ozone levels will rise by an annual average of 0.43 ppb from the year 2040 through 2050. The study concluded that this increase will be due from climate change alone and will result in an increase of 0.01 percent in mortalities.

    Death Rate and Ozone Levels

    • The same information from NARCCAP was interpreted by a group of researchers from Yale University, who controlled the study for factors such as weather, seasonality and particulate matter in the air. Their results were published in the November 2004 issue of "JAMA: The Journal of the American Medical Association." They concluded that an increase of 10 ppb was associated with a 0.64 percent increase in the death rate due to cardiovascular and respiratory diseases.

    Exposure to Increased Amounts of Ozone

    • A study appearing in the January 2010 issue of "Environmental Health" investigated the effects of ozone on the population of eastern Massachusetts from 1995 through 2002. The study analyzed more than 150,000 non-accidental deaths and found that an increase of 10 ppb of ozone leads to almost a 2 percent increase in all natural deaths. The researchers further found that their results had no correlations to socioeconomic status or sub-populations.

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