Fracking doesn’t consist of large, stationary pollution sources, like U.S. Steel’s metallurgical coke plant in Clairton, where emissions are monitored daily, the pollutants they contain are known and the health effects of those pollutants are well understood from decades of research.
Fracking’s effect on regional air quality and health is a puzzle of factors that in many cases are still poorly documented and understood. But researchers are starting to put together the pieces.
Nearly 80 published studies have investigated fracking’s impact on air quality and health, and more than 8 in 10 report that fracking poses risks to both. Still unclear, however, is the level of risk.
Air Quality Impact
The range of emissions typically released from fracking operations is largely known and includes major pollutants regulated by the U.S. Environmental Protection Agency, such as fine particulates, as well as chemicals identified as hazardous air pollutants, these include, which are known or suspected to cause cancer and other health conditions.
Those pollutants tend to vary depending on the source. Diesel emissions, for example, are usually the greatest when heavy trucks and machinery are used to prepare well sites. Diesel emissions contain many toxic chemicals, most notably fine diesel particulate matter, which can increase the risk of asthma attacks, heart and respiratory disease, adverse birth outcomes and premature death. Diesel emissions from fracking were significant enough that the National Institute for Occupational Safety and Health identified diesel particulates as a hazard for oil and gas workers based on readings at oil and gas sites in five states, including Pennsylvania.
Hazardous air pollutants can be emitted from fracking sources such as condensate tanks, diesel trucks and wastewater impoundment pits. Exposure to this class of pollutants, which includes benzene and toluene, is linked to effects ranging from cancer to high-risk pregnancies and asthma. The precise health risks the pollutants pose depend on a number of factors, including concentration, proximity to the pollution source and length of exposure.
A recent study commissioned by the West Virginia Department of Environmental Protection, for example, found that in several cases benzene concentrations 625 feet from gas drilling activity were above the “minimum risk level” for the pollutant set by the Centers for Disease Control and Prevention to identify potential health concerns.
Some fracking emissions can have broader impact, particularly those that contain nitrogen oxides and volatile organic compounds, two ingredients of ground-level ozone, a far-traveling pollutant. Ozone levels in southwestern Pennsylvania exceed EPA limits. Studies suggest exposure to ozone raises the risk of respiratory conditions, cardiovascular disease and other health problems.
Fracking operations are the major source of volatile organic compounds emitted in Butler, Fayette, Greene and Washington counties, which hold the majority of natural gas wells in southwestern Pennsylvania, according to state Department of Environmental Protection data.
Some 46 studies that looked at how fracking affects air quality were published from 2009 to 2015, according to a 2016 survey of peer-reviewed research in the journal, PLoS ONE. Of those, 87 percent linked fracking to higher levels of air pollution. The rest found no evidence fracking resulted in higher emissions or concentrations of air pollutants.
Fewer studies examined the public health impact of fracking using epidemiological data, self-reported symptoms and other sources. Of the 31 studies that did, 84 percent reported findings that suggest a link between fracking and elevated health risks and poor health outcomes.
In most cases, people most vulnerable to fracking’s public health impacts are closest to the emission sources, research suggests. But the variety of emission sources, some of which are mobile, and other factors make identifying the at-risk population difficult.
“What we don’t know is how people may be exposed,” said Sam Rubright, at Fractracker Alliance, a nonprofit that studies oil and gas production. “We’re talking about citizens and residents who live near the well site and workers. We don’t know exactly how people are exposed to these compounds because exposure is going to vary so much.”
Research does, however, identify areas of concern that warrant further investigation.
Johns Hopkins University researchers, for example, used data from the Geisinger Health System to compare birth weight to the distance between pregnant women’s homes and well pads. The women were a representative sample based on age, sex, race/ethnicity, and rural residence. Their babies were delivered at two hospitals in Pennsylvania’s North Central region. The sample was adjusted for other factors, including the socio-economic status of the women. Geographic comparisons were made to examine birth weight of infants born to the women. Women were 40 percent more likely to give birth before 37 weeks when they lived in the areas with the highest fracking activity compared to the surrounding zip codes, and 30 percent more likely to have a high-risk pregnancy.
University of Pittsburgh researchers reported that babies born in the areas with the greatest exposure to fracking activities were 34 percent more likely to be small for gestational age compared to those born in places with the least exposure. The findings are based on birth records in Washington, Westmoreland and Butler counties from 2007 to 2010.
And last year, the federal Occupational Safety and Health Administration revised standards to limit workers’ exposure to silica based on a study that found that gas and oil workers are at high risk of inhaling the chemical compound when working near frack sand used to hold open the cracks created in the fracking process. Inhaling silica can cause lung disease, silicosis and cancer.
The degree of risk people face from air pollutants depends on many factors, including the kind of pollutant, the exposure level and duration, and the person’s age and health.
The Known Unknowns
With fracking operations, a shortage of key data has hampered efforts to more precisely measure the level of risk emissions pose to public health.
One reason for uncertainty surrounding exposure levels is that vast differences in emissions are found from one well site to the next, even among those owned and operated by the same company. And unconventional natural gas wells are not considered major sources of air pollution by the EPA. There is no required air quality monitoring and reporting for the industry, even for fixed sources, such as compressor stations used to keep the pipeline pressurized and separate the gases.
“Risk is a function of exposure and toxicity,” said Bernard Goldstein, professor emeritus at the University of Pittsburgh School of Public Health. “We know about the toxicity of the chemicals, the hazard of the chemicals. But without understanding exposure, we don’t know risk.”
In the absence of industry– wide monitoring, researchers and local public health projects have begun collecting their own data. In Washington County, for example, the Southwest Pennsylvania Environmental Health Project collects air quality data mostly by using at-home SPECK air monitors spread across more than 400 households to better understand exposure and understand the risk to communities.
“What does an exposure pattern look like?” asked Raina Rippel, director of the project. “What is it like if you’re within one kilometer of a fracking well? If you’re within one kilometer of multiple installations, pipelines, compressor stations, metering stations? People are being exposed to emissions from the traffic to and from well pads, to compressor stations, to chemicals used during fracking and to various operations that happen before and after — drilling the borehole, the flow-back. There’s this whole spectrum of activity and there seem to be different health symptoms that happen during those different periods.”
Research is increasing. And major ongoing studies, such as the Johns Hopkins investigation of links to asthma and pregnancy outcomes, are expected to help shed more light on the impact of fracking on nearby communities. In the meantime, uncertainty remains for those in the shale gas fields of southwestern Pennsylvania.
“One of the major issues is that studies that look at emissions show marked variability from site to site. And it’s not very clear as to why that is,” Goldstein said. “What do you tell someone who is worried? Be lucky and be near the site that’s hardly emitting anything and not the one that’s emitting a lot?”