Hydraulic fracturing, an industrial process that involves breaking rock formation deep underground to extract fossil fuels, has gained a lot of controversy over the past years because of its reported negative impacts on the environment and human health.

Aside from increasing the levels of toxic radon, contributing to earthquake occurrences and contaminating drinking water, the process, more known as "fracking," has also been associated with increased levels of air pollution. In line with this, a new study revealed that it can also worsen asthma attacks.

Published in the journal JAMA Internal Medicine, the study was conducted by the researchers at Johns Hopkins Bloomberg School of Public Health.

For the study, the group analyzed health records from 2005 through 2012 from the Geisinger Health System in Pennsylvania. After the analysis, they noticed that asthma attacks over the years have increased. Identifying the locations of those individuals, they found out that those who live nearby fracking areas suffered more attacks than those who live far off.

The study revealed that people living near fracking sites experienced asthma attacks 1.5 to 4 times higher than those in areas with low fracking activity.

American Lung Association notes that millions of Americans are suffering from asthma. With fracking being rampant in a number of states, the risk is much more elevated.

"Ours is the first to look at asthma but we now have several studies suggesting adverse health outcomes related to the drilling of unconventional natural gas wells," said study leader Sara G. Rasmussen, MHS, a PhD candidate in the Bloomberg School's Department of Environmental Health Sciences, in a press release.

"Going forward, we need to focus on the exact reasons why these things are happening, because if we know why, we can help make the industry safer," she said.

The author added they cannot pinpoint the particular reason why asthma attacks increase near fracking sites but they have speculated that air pollutants brought by the activity has something to do with them.

"We believe it is time to take a more cautious approach to well development with an eye on environmental and public health impacts," said the study's senior author, Brian S. Schwartz, MD, MS, a professor in the the same department as Rasmussen at Bloomberg.