Public Release: 

Unconventional natural gas development associated with increased asthma exacerbation risk

The JAMA Network Journals

Residential unconventional natural gas development activity, a process that involves fracking and creates a source of energy used both domestically and internationally, was associated with increased risk of asthma exacerbations in a study of patients with asthma in Pennsylvania, according to an article published online by JAMA Internal Medicine.

Asthma is a common chronic disease with nearly 26 million people in the United States with asthma. Outdoor air pollution is recognized as a cause of asthma exacerbations. Unconventional natural gas development (UNGD) has been associated with air quality and community social impacts, such as air pollution from truck traffic and sleep disruption.

Pennsylvania has moved rapidly with UNGD and more than 6,200 wells were drilled between the mid-2000s and 2012. However, few studies have been published on the public health impacts of UNGD.

The steps of UNGD include well pad preparation, drilling, stimulation (also called fracking) and gas production.

Brian S. Schwartz, M.D., M.S., of the Johns Hopkins Bloomberg School of Public Health, Baltimore, and coauthors looked at associations between UNGD and asthma exacerbations.

The authors compared patients with asthma with and without exacerbations from 2005 and 2012 who were treated at Pennsylvania's Geisinger Clinic. The study included 35,508 patients identified in electronic health records.

The authors estimated activity metrics for the four phases of UNGD (pad preparation, drilling, stimulation and production) using the distance from patients' homes to the wells, well characteristics and the duration of phases.

Between 2005 and 2013, 6,253 unconventional natural gas wells were spudded (the start of drilling) on 2,710 pads; 4,728 wells were stimulated and 3,706 were in production.

The authors identified 20,749 mild (new oral corticosteroid medication order), 1,870 moderate (emergency department visit) and 4,782 severe (hospitalization) asthma exacerbations and matched those to control index dates for comparison.

Patients with asthma in areas with the highest residential UNGD activity had higher risk of the three types of exacerbations compared with those patients in the lowest group of residential activity, according to the study results.

Study limitations include that the electronic health record did not have information on patients' occupations and only reflects patients' most recent address.

"Asthma is a common disease with large individual and societal burdens, so the possibility that UNGD may increase risk for asthma exacerbations requires public health attention. As ours is the first study to our knowledge of UNGD and objective respiratory outcomes, and several other health outcomes have not been investigated to date, there is an urgent need for more health studies. These should include more detailed exposure assessment to better characterize pathways and to identify the phases of development that present the most risk," the study concludes.

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(JAMA Intern Med. Published online July 18, 2016. doi:10.1001/jamainternmed.2016.2436. Available pre-embargo to the media at http://media.jamanetwork.com.)

Editor's Note: The article contains conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Media Advisory: To contact study author Brian S. Schwartz, M.D., M.S., call Barbara Benham at 410-614-6029 or email BBenham1@jhu.edu.

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