The 20 miles of interstate highway between the small towns of Silt and Parachute in western Colorado slice through a landscape of sagebrush and mesas. There are few exits through this section of Garfield County, where the local population of deer and elk rivals the number of ranchers, retirees and others who live here.

Susan Haire, 55 and a small-scale rancher, lived on top of one of the surrounding mesas for nearly a decade, but she says that in the last year, the landscape turned against her. When she drove down this stretch of highway, her nose bled, her eyes burned and her head pounded. She began wearing a respirator to clean the air in her car.

"I felt like an alien, like I didn't fit into my own environment," says Haire. "It's horrifying what's happening here. The changes that have happened in the past 18 months are so dramatic, it's just a nightmare."

Haire's doctor blamed her ill health on the changes that occurred around her: In the last two years, gas companies have drilled over 600 natural gas wells. Every few feet, 150-foot-tall drill rigs — all flying American flags — rise upwards into the sky. Banks of rectangular huts with five-foot diameter fans sit back from the road, pumping and moving the gas into underground pipelines.

Haire's experience isn't unique. Veteran oil and gas lawyer Lance Astrella of Denver, who has built a career fighting the industry on behalf of citizens, says he has talked with dozens of people who blame their health problems on the surge of new gas wells. Between January and March of this year, eight people called the Garfield County oil and gas department to complain about air quality. They asked about black smoke and strong chemical odors that they worried could make them sick.

Critics say health hazards from the wells don't stop with air pollution. They point to a process called hydraulic fracturing, whereby a gas company injects into the ground a mix of water, sand and chemicals that include carcinogens such as benzene, arsenic and lead. Developed by Halliburton, hydraulic fracturing, commonly called "frac'ing," loosens the rock and maximizes the flow of gas to the surface. But up to 40 percent of the fracturing fluids remains in the formation, according to studies conducted by the Environmental Protection Agency and the oil and gas industry. That means that toxic fluids could seep into the surrounding soil, groundwater and into water wells.

In Garfield County, there are at least 2 trillion cubic feet of natural gas in the tight sand and coal bed formations below, according to gas companies and industry geologists. Over the next eight years, over 10,000 additional wells are slated for drilling in the county. Today, federal and state agencies in Wyoming, Colorado and New Mexico are issuing more permits to drill for gas than ever before, and doing it as quickly as possible, under orders from Washington. The Bush administration says finding energy at home is critical to reducing foreign imports and ensuring national security, and in the aftermath of Hurricane Katrina, Congress has pushed to increase energy sources beyond the reach of the coastline.

Despite the potential for health problems from unregulated pollution, neither the Centers for Disease Control nor the Environmental Protection Agency is conducting long-term public health studies connected to all this drilling. So no one knows how natural gas development may be polluting the air or water or affecting human health.

In the meantime, Haire — who just moved to Texas for her health — and the neighbors she left behind, aren't lone voices: In 2004, a group of 18 top public health experts alerted the EPA and Interior Department officials that accelerated oil and gas drilling in the West was taking place without adequate regard for human health. The warning was not heeded.

One agency staffer, who plans to retire soon, speaks out bluntly: "It's a catch-22: If the EPA doesn't study the health impacts, then there's no proof anything dangerous happening is happening. That's irrational and corrupt," says Wes Wilson, an environmental engineer with the EPA's Denver office for the past 32 years. He calls his agency's position sad: "We used to investigate mysteries and now we're not. It's kind of like we're being paid off with our generous salaries. The American public would be shocked if they knew we (at EPA) make six figures, and we basically sit around and do nothing."

Rebecca Clarren is a contributor to Writers on the Range, a service of High Country News (hcn.org). She writes about health and environmental issues in Portland, Oregon.