An eight-year-long study concludes fracking may worsen asthma in children and adults who live near sites where the oil and gas drilling method is used.
But it did not establish that fracking directly caused or worsened asthma.
Researchers from Johns Hopkins University found that asthma treatments were as much as four times more common in patients living closer to areas with more or bigger active wells than those living far away.
They believe pollution and stress from the noise caused by fracking might explain the results.
The Canadian Press