Asthma patients are 1.5 to four times more likely to have asthma attacks if they live near bigger or a larger number of unconventional natural gas development wells, according to a study
published Monday in the Journal of the American Medical Association Internal Medicine.
The researchers at Johns Hopkins University partnered with Geisinger Health System and conducted the study using electronic health records from 2005 to 2012 in north and central Pennsylvania.
Among the 27,000 identified asthma cases with patients age 5 to 90 that met the study's criteria, about 20,000 were categorized by the researchers as having mild attacks (new oral corticosteroid orders), 1,800 were moderate attacks (emergency room visits), and 4,700 suffered from severe attacks (hospitalizations).
Pennsylvania has seen rapid unconventional natural gas development in recent years, with more than 6,200 wells being drilled from the mid-2000s to 2012. The study researchers assigned each well metrics based on location, depth, number, developmental phases and production volume and length data obtained from state departments.
They then mapped out the wells and the location of the asthma patients and compared them with patients who did not have asthma attacks in the same year.
The study found associations between increased risks of asthma attacks and living close to more or bigger natural gas wells across all four stages of development: well pad preparation, well drilling, stimulation (the stage commonly referred to as fracking) and production. Asthma patients who live near wells that are in the production phase, which can last for years, are at greater risks.
The findings are robust even after taking into consideration factors such as family history, smoking, socioeconomic status and proximity to major roads.
The current study does not explain the exact medical causes behind their findings, explained the study's lead author, Sara Rasmussen, a Ph.D. candidate at Johns Hopkins University. Residents living near natural gas wells are exposed to a variety of negative influences, such as psychosocial stress, noise, heavy truck traffic, sleep disruption and air pollution.
She said more research needs to be done to find out how stress and air pollution affect the relationship between the worsening of asthma and nearby fracking wells.
But she said the study adds to a growing body of evidence that links unconventional natural gas development to adverse health outcomes, such as preterm births
, low birth weight
and skin and respiratory problems
. "This is the first study of objective respiratory outcomes and its relationship with unconventional natural gas development," Rasmussen said.
Rasmussen said that since the research project did not single out how far away residents live from development wells as a separate factor, "we can't really give recommendations on a safe distance." She suggested concerned patients speak with their doctors about their condition.
"Going forward, everyone can learn from Pennsylvania's experience," said Brian S. Schwartz in a news release
, the study's co-author and a professor in the Department of Environmental Health Sciences at Johns Hopkins. "State regulatory bodies should use the growing number of health studies to understand the possible environmental and public health impacts of this industry and how to minimize them."