According to research from USC’s Keck School of Medicine, pregnant women living within three-miles of a natural gas or oil well and exposed to frequent “gas flaring” had a 50% greater risk to give birth prematurely.

Gas flaring is a process of burning gases during oil and gas operations, including oil and gas recovery, coal bed methane production, petrochemical process and landfill gas extraction, according to

Flares, which can burn for weeks at a time, release harmful chemicals such as benzene as well as fine particle pollution, carbon monoxide, nitrogen oxides, heavy metals and black carbon. Several of these combustion-related pollutants are linked to a higher risk of preterm birth and reduced birth weight in other contexts.

“Our study finds that living near flaring is harmful to pregnant women and babies,” said Jill Johnston, an environmental health scientist at the Keck School of Medicine of USC. “We have seen a sharp increase in flaring in Texas’ Eagle Ford Shale, and this is the first study to explore the potential health impacts.”