PITTSBURGH (KDKA) – Fracking may worsen asthma in children and adults who live near oil and gas drilling sites according to a new Pennsylvania study.

The eight-year study found that asthma treatments were as much as four times more common in patients living closer to areas with more or larger wells than those living further away.

The study could not establish that fracking directly caused or worsened asthma.

There’s also no way to tell from the study whether asthma patients exposed to fracking fare worse than those exposed to more traditional gas driving methods.

Sara Rasmussen, the study’s lead author and a researcher at Johns Hopkins University’s Bloomberg School of Public Health, said pollution and stress from the noise caused by fracking might explain the results.

But the authors emphasized that the study doesn’t prove what caused patients’ symptoms.

Previous research has found heavy air pollution in areas where oil and gas drilling is booming.

Read more from CBS News here.