There are about 1.1 million active oil and gas wells in the U.S., with thousands more drilled every year. Most of the new ones use so-called fracking techniques to crack open rock that has natural gas trapped inside. Environmentalists have long complained that pollution rules haven't kept up with the new drilling techniques and the gas-drilling boom. Ramon Alvarez is with the Environmental Defense Fund in Austin:
"Natural gas production involves kind of a soup of chemicals. Natural gas is not just methane. Some of the pollutants that are problematic are those that are called volatile organic compounds, those contribute to the formation of ground-level ozone which you see big problems in areas like Dallas, Fort Worth and Houston."
The new rules would require gas companies to install equipment to prevent leaks and capture gases. Gas can leak from drill pads, storage tanks, and even pipelines and processing plants. When methane leaks out, it contributes to global warming. But Alvarez says the more urgent worry comes from toxic hitchhikers that are mixed in with the oil and gas.
"Then you also have individual chemicals like benzene or hexane, that are directly harmful to human health. They're air toxics, some of those cause cancer, they also can have neurotoxic affects. So just directly harmful to public health. And those tend to be localized right around the production or processing activities."
Some states, like Colorado and Wyming, already require drillers to use new pollution-control equipment. The EPA rules would apply to the whole country. Because of a lawsuit, the agency is under a court order to finalize the rules by February.