This week, the Environmental Protection Agency released guidelines for oil and natural gas companies to measure and report the greenhouse gas emissions produced by their operations annually.

The final rule says that oil and natural gas facilities that emit 25,000 metric tons of carbon dioxide equivalent or more per year must track that information starting in January and report it to the EPA annually, beginning March 2012.

The EPA rolled out the requirement for certain industrial operations, such as cement and steel manufacturers, in January. It took some more time to finalize the rules for oil and gas reporting.

What does that level of emissions mean? For perspective, the EPA offers this comparison for 25,000 MTCO2e:

* Annual greenhouse gas emissions from the energy use of approximately 2,300 homes

* Annual greenhouse gas emissions from approximately 4,600 passenger vehicles

About two weeks ago, the Pennsylvania DEP published the results of some short-term air sampling at Marcellus Shale gas compressors and condensate tank sites in Washington and Greene counties done this spring. It did not find levels dangerous to human health.

The full report can be downloaded here.

It spells out the data in parts per billion and micrograms per cubic meter. Natural gas operations emit methane and other “anes” such as ethane, propane and ethane, in smaller measures.

The DEP report helpfully outlines which parts of natural gas extraction and processing can cause emissions:

* Pad, impoundment and road construction: emissions from diesel engines from trucks and construction equipment.

* Dilling: emissions from diesel engines.

* Fracing: emissions from diesel engines, evaporation of wastewater.

* Flaring: emissions from burning gas.

* Condensate tanks: emissions from venting during tank filling.

* Compressor stations: emissions from diesel engines, fugitive emissions from compressor equipment, pipes and tanks are possible.

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