The data come from a report released by the Pennsylvania Department of Environmental Protection. The 2014 numbers are the most recent available data and are self-reported by the Marcellus shale industry.
DEP officials said the increase in emissions makes sense, considering the growth of the natural gas industry at the time.
“We’re seeing more build out of pipelines and other natural gas infrastructure in the state, so with that sort of increase in production, you would expect to see an increase in some of the different pollutants associated with natural gas development,” DEP Spokesman Neil Shader said.
Gas production increased by about 30 percent in 2014, with 508 midstream facilities submitting data -- an increase of 61 facilities from the prior year.
From 2013 to 2014, the DEP found increased emissions from of carbon monoxide by 25 percent, or from 6,606 tons to 8,228 tons and an increase of volatile organic compounds by 33 percent, or from 4,790 tons to 6,388 tons.
In the same time, the DEP found decreased emissions of nitrous oxide by 54 percent, or from 77.8 tons to 36 tons and of toluene by 6 percent, or from 43.5 tons to 41 tons.
The emissions tracked by the DEP have all been linked to negative health impacts. In the case of toluene, short-term exposure to higher levels can cause headaches and coughing. Prolonged exposure can cause nervous system and liver damage, according to the EPA. Volatile organic compounds are created throughout the combustion process, but are also found in consumers products, including paint. The EPA said exposure to volatile organic compounds can cause eyes and nose irritation and cause cancer over time.
“What we’re looking at is emissions coming off of things like the engines that drive compressor stations or some of the machinery that operates at well sites,” Shader said.
The report also looked at methane that leaks from pipelines and equipment during productions and transportation. Those emissions were up by 1 percent.
In Allegheny County, emissions for things such as benzene and volatile organic compounds were up, but for most of the other categories, such as carbon monoxide and nitrous oxide, they were down.
For Washington County, which had some of the highest emissions in the state, emissions were up in every category other than volatile organic compounds, n-hexane and nitrous oxide.
Though numbers are self-reported, Shrader said DEP officials are confident in their accuracy.
“We get so much information that we do feel confident in it,” Shader said.