A proposed study of people in northern Pennsylvania could help resolve a national debate about whether the natural gas boom is making people sick.
The study would look at detailed health histories on hundreds of thousands of people who live near the Marcellus Shale, a rock formation in which energy companies have already drilled about 5,000 natural gas wells.
If the study goes forward, it would be the first large-scale, scientifically rigorous assessment of the health effects of gas production.
Living in the middle of a natural gas boom can be pretty unsettling. The area around the town of Silt, Colo., used to be the kind of sleepy rural place where the tweet of birds was the most you would hear. Now it's hard to make out the birds because of the rumbling of natural gas drilling rigs.
The land here is steep cliffs and valleys. But bare splotches of earth called well pads are all over the place.
"That's the one I'm worried about because it just went in," says Tim Ray.
World oil prices have been falling recently — and that's good news for oil consumers such as the U.S., Europe and China, and a potential challenge for the big exporters like Saudi Arabia and Russia.
The oil market is notoriously volatile, and the factors driving prices down are temporary. But some energy industry analysts are posing a much larger question: Is the world, and the U.S. in particular, entering a new phase of expanding energy supplies and more moderate prices?