As I wrote here, a recent study from the RAND Corporation found that air pollution from natural gas development in Pennsylvania (excluding methane emissions) is relatively small compared to some other major sources of air pollution - like coal-fired power plants. So far, anyway.
Indeed, state data from 2011 shows that air emissions associated with Marcellus Shale production are a “small fraction of air pollution in the state.”
But the 2011 data conforms what RAND found - that emissions from natgas development are nevertheless "a concern in regions of signiﬁcant extraction activities."
An excellent article in the Wilkes-Barre Citizens Voice shows just how big the concern is, and why emissions data must be considered in the aggregate AND in local contexts. After all, "local" is where people live.
Pennsylvania's Bradford and Susquehanna counties led the state in 2011 in the volume of air pollution released by production and processing of shale gas - nitrogen oxides (NOx), carbon monoxide, sulfur oxides and total shale-related air pollution.
NOx pollution contributes to the formation of ground-level ozone – the main component of smog - fine particle pollution, and is linked with a number of adverse effects on the respiratory system. In Bradford, 2,600 tons of shale-related NOx were emitted in 2011 - more than ten times the amount released by ALL other sources in the county. In Susquehanna County, 2,440 tons of NOx were emitted in 2011 from gas production and processing, and the only other reported source - at 17 tons - was a compressor station on the Tennessee Gas Pipeline.
As the Citizens Voice article points out:
(t)he combined shale-related nitrogen oxide emissions in Bradford and Susquehanna counties - 5,000 tons - are nearly a third of the statewide shale-related NOx of 16,500 tons. Both together and separately, they surpass the single-largest industrial source of NOx pollution in the 11-county northeast region, GenOn Energy's Portland Generating Station, a coal-fired power plant in Northampton County that emitted 2,000 tons of NOx in 2011, according to DEP facility reports.
So, while natgas-related emissions are small overall, they are very significant locally. They must be looked at in both ways – especially because they’re going to grow as development proceeds - and they must be minimized with measures like regulations requiring best available control technologies on all gas-related equipment.