Preventing leaks also cuts back on other air pollutants associated with gas production and use, including such volatile organic compounds as ethane and butane.

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The debate surfaced a policy difference on the so-called mercury standard, EPA regulations to limit mercury and other air pollutants from power plants that have been linked to childhood asthma and other health problems.

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These are the first national standards to require use of modern control technologies to reduce mercury, arsenic, lead, hydrochloric acid and other hazardous air pollutants from coal plants.

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The EPA regulates other pollutants under the Clean Air Act, but not this.

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It also releases double the other pollutants regulated by the Clean Air Act that include sulfur dioxide and nitrogen oxide.

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But Russell Train, who served as EPA administrator in the Nixon and Ford administrations, counters that carbon dioxide is no different than other natural substances in the air that have been deemed pollutants and regulated in the past.

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He says the Clean Air Act, which is designed to regulate traditional air pollutants, is the "wrong horse" for regulation of CO2 and other greenhouse gases.

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