Regional Air Emissions Data


Since we are now able to access two years of natural gas emissions inventory, we have data we can review to get a better idea of how our air is changing in the Northern Tier.  Unless otherwise noted, all the data for 2005-2010 is directly from DEP’s Efacts.   The data for 2011-2012 is the total of Efacts data plus the Natural Gas Emissions Inventory.   It is important to note, that since there was no reported natural gas emissions inventory prior to 2011, the data spikes on these graphs.  It may not necessarily be as sharp in reality, as there was a gradual change, since emissions were unreported since drilling began in 2006 through 2010.

Please note greenhouse gas emissions are first reported in 2012.  Since there is no prior year to compare, we are not reviewing this data this year.

Northern Tier Region Air Quality

Now, let’s take a look at the Northern Tier Region’s air quality.   First, let’s just look at County Total Emissions from 2005-2012.  Keep in mind, the first unconventional wells were drilled in Bradford, Susquehanna & Tioga Counties during 2006 (DEP Spud Wells Reports).  Our graphs start in 2005.  Normally, we don’t see emissions totaled together.  Each have different thresholds and health effects.  The only reason we total them is to provide an idea of the changes.


Since our counties range in size, to get a better idea of the emissions to compare apples to apples the concentration of emissions, we break them down by square miles, knowing full well these emissions will travel beyond the county line.  This is just to provide a better idea of how our air is changing in each county.


County Specific Air Emissions

Now, we are going to show the state of air in each county.   Please note, formaldehyde is indicated as HCHO on these graphs.

How do Spud Wells Correlate?

To develop a better understanding of these charts and our air quality, we now look at spud wells on a school-year basis.  There is a very good reason why we do this, so stay tuned.


We see from this graph that the emissions are somewhat following the drilling.  We are also transitioning from intermittent sources – drilling and fracturing to more permanent sources such as compressor stations, dehydration facilities and producing wells.

We don’t, at least the general public doesn’t have access to health data to see what impact air quality may be having in our region.  One statistic we do have is data related to school students with medical diagnosis of asthma. We’ve been paying attention to this.  Now, we have enough information to really take a look at it.


Northern Tier Region Air Quality – Looking Deeper into the Data

The Northern Tier’s regional total emissions decreased from 2011 to 2012 by 19.3%.  Now, this is interesting.  We know there is less drilling.  But, what else can we see in this number?  Efacts data indicates a small increase in emissions for both Bradford & Wyoming Counties, while a small decrease is noted for both Susquehanna & Tioga.

The 2012 data is providing food for careful and serious thought.  Overall, the statewide natural gas emission totals increased 1,768 tons.  But, here in the Northern Tier, our natural gas emissions decreased by 3,056 tons.  It is more telling to review the changes too. DEP notes that the VOC’s increased 42.7%.  Likely this increase is somewhat influenced by the “250 additional compressor stations that process gas from traditional well sites. These compressor stations were not required to report in 2011.”    This is really evident as many of those compressor stations were not located within the Northern Tier Region, where we actually had a decrease in VOCs by 83.3 tons.   Every county but Sullivan experienced a decrease, however Sullivan’s increase was only 1 ton, and their total VOC’s totaled 11 tons in 2012.

Compressor Stations – of the total Northern Tier emissions these amounts are attributed to compressor stations located in the Northern Tier:

  • 466 tons or 15.8% of the total CO emissions
  • 1,041 tons or 14.9% of the total Nox emissions
  • 48 tons or 6.9% of  the total PM-10 emissions
  • 45 tons or 10.5% of the total PM-2.5 emissions
  • 3 tons or 3.1% of the total SOx emissions
  • 431 tons or 28.9% of the total VOC emissions
  • 2 tons or 33.2% of the total Benzene emissions
  • 2 tons or 62.5% of the total Ethyl Benzene emissions
  • 101 tons or 82.9% of the total Formaldehyde [HCHO] emissions
  • 3 tons or 44.6% of the total n-Hexane emissions
  • 3 tons or 43.1% of the total Toluene emissions
  • 3 tons or 56.6% of the total Xylenes emissions
  • .7 tons or 99.7% of the total 2,2,4 Trimethylpentane emissions

It was intended to insert a pie chart here of what a typical compressor station is emitting.  It was decided not to do that as there is no easy way to determine what is typical. There is a broad range of what is occurring throughout the Northern Tier.  During 2012 many compressor station locations were free flowing gas, not using engines and so emissions are very minimal. There are others that did have engines employed, and emissions vary greatly with those facilities.  The best information we can provide easily is noted above.  Anyone interested in what is emitting from the compressor station nearby their home, can certainly review the data, but please keep in mind this data is two years old and may not be relevant to current operations.  Since 2012, stations have been transitioning from free flowing gas to the employment of engines, while others may have added additional engines.   On the 2012 inventory, there were 70 locations; compressor stations, dehydration stations and interconnects that were recorded on the emissions inventory in the Northern Tier region.

DEP provides the natural gas emissions inventory in several formats that provide for a little easier review.   A review of the Emissions by Source Type in comparison to the 2011 data reveals some interesting information.  Keep in mind this is statewide data.  In 2011, the top three sources of emissions came from drilling rigs, 40.3%; completions & workovers, 33%; and stationary engines, 19.5%. These three sources represent 92.8% of the total natural gas emissions.

In 2012, the top three sources of emissions came from engines, 32.4%; drilling rigs, 28.6% and completions, 27.1%.  These three sources represent 88.1% of the total natural gas emissions.

While some may desire to compare our data to other counties within PA, after careful consideration, we determined not to do this.  Why?  Well, because we know that our region has had very minimal emissions prior to Marcellus Shale development.  Further comparing to other areas does nothing to show how our region is changing.  Thus, the best comparison we can do is to stick with our analysis of how our regional air quality is changing and review those statistics.

Therefore, we reviewed the emissions inventory common pollutants for 2011 and 2012.  Then based on what we were seeing, we looked further at the air toxics emissions from 2005-2012, which are indicated on this below graph.  Please note, formaldehyde is indicated as HCHO on the graph.


And finally, one last bit of consideration is What is our portion of the Commonwealth’s total natural gas emissions?  Well folks, this is where we probably have the advantage of high pressured gas free flowing from compressor stations and the advantage of very dry gas requiring less processing.  Through 2012, our region hosts 44.2% of the total unconventional spud wells.  However, as noted on the below chart, our emissions experience is quite different.



Actually, this is pretty good news for 2012.  With the entrance of any industry, air quality is affected.  What we are seeing in 2012 is that our emissions decreased and the asthma rates are also somewhat partly beginning to indicate a downward turn.  We are seeing our region is experiencing a lesser portion of the emissions as compared to the percentage of hosted spud wells.  We are still in the beginning of the development, so, it is good to see we are not seeing significant statistics.  The Bureau of Air Quality noted that while they’ve been monitoring for winter ozone, there has been no indication in our region of winter ozone*.  They noted that if it were to occur, the weather we experienced this past winter would have indicated such.  There are many areas of the state still with significantly worse air quality than our region despite these changes.  So, this is good news considering all the changes here.

*Power Source Pittsburgh Post Gazette- DEP says air emissions from gas drilling flat

However, that being said, this data is practically two years old.  So we have no idea what our air quality is today.   We do have more monitors.  With such changes, including increasing levels of air toxics and particulate matter, we need a complete air monitoring system in the Northern Tier.  We need to have such a system so that our region is placed on alert when yellow or orange air quality action days may occur.  Parents of asthmatics and those with respiratory challenges of all ages need that information when living in the Pennsylvania gas fields.  We need that information in the Northern Tier Region.

Finally, for those who are interested in further reading concerning air toxics, we’ve included these fact sheets for pollutants on the air emissions inventory.

Other Resources

Fact Sheets for pollutants reported on the emissions inventory and common to the Northern Tier region.



PM10 & PM2.5

Agency for Toxic Substances and Disease Registry