Emissions Inventory

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What is an Emissions Inventory?

An emissions inventory is a detailed list of air pollutant emissions associated with the various sources of emissions. Emissions sources are designated as either stationary or mobile sources. Stationary sources are categorized as either point sources, which emit a confined air stream through a stack or pipe, or area sources, which are numerous small activities that are not individually tracked. Point sources include stationary sources at manufacturing facilities and power plants. Typical area sources are gasoline stations, dry cleaners, wood stoves, forest fires and house paints. Mobile sources are categorized as on-road or off-road. On-road mobile sources include passenger vehicles, motorcycles and trucks; off-road sources include construction equipment, lawn mowers, chainsaws, snowmobiles and motorboats.

Emissions are identified with a source in terms of the type of pollutant and the quantity of emissions. Pollutants maintained in DEEP's air inventories include traditional or criteria pollutants (e.g., nitrogen oxides, volatile organic compounds, sulfur dioxides, particulate matter), toxic air pollutants (e.g., mercury, ammonia, benzene, dioxide) and greenhouse gases (e.g., carbon dioxide, methane). Specialized methods have been developed to calculate individual pollutant emissions associated with each source category. The resulting information can be aggregated and sorted to assess emissions trends, ambient impact analysis and inform planning.

More background on emissions inventories is available from the U.S. Environmental Protection Agency (EPA) at the following location: EPA Emissions Inventory

Why Does CT Compile and Maintain an Emissions Inventory?

Air emissions inventories are crucial to DEEP's efforts to improve Connecticut's air quality in furtherance of public and environmental health. Air emissions inventory information assists in planning to reduce emissions to meet federal and state mandates, tracking Connecticut's progress towards meeting our air quality goals, and mitigating significant impacts of air pollution.

What are DEEP's Current Inventory Actions?

Periodic Emissions Inventory (PEI)

The EPA requires a PEI every three years. The PEI quantifies actual air emissions for all categories of air pollution sources in Connecticut. Below is the Department of Energy and Environmental Protection's submittal for the 2011 PEI.

Emission Statement Requirements

DEEP requires the owners of stationary sources of nitrogen oxides and volatile organic compounds with actual emissions of at least 25 tons per year to report the actual emissions from the source each year. Connecticut certifies such requirements to EPA as part of its ozone nonattainment planning requirements. Below is the emission statement certification for the 2008 ozone national ambient air quality standard, dated September 5, 2017.

Emission Statement Certification

Point Source Inventory

DEEP obtains point source emissions information through an electronic annual emissions statement report that is submitted by the owner of a source of air pollution in the state. Annual data reporting begins in the first quarter of the year for the annual data of the preceding year.

Every Title V source owner and other mandated emissions reporters must designate a single person (a submitter) who is legally authorized to submit an emissions statement to DEEP. Each mandated reporter may also designate one or more persons (editors) who develop the information used in the annual emissions statement. Each submitter or editor must register with DEEP by completing and submitting the appropriate application form. Each submitter and editor will be given a User Name, ID and Password upon registering.

Greenhouse Gas (GHG) Inventory

The U.S. Environmental Protection Agency (EPA) has a mandatory reporting program for GHG emissions from major point sources. More information about this program can be found here.

EMIT Emissions Inventory

Link to EMIT Website

NoteIt is recommended to use Google Chrome when accessing EMIT. Use of alternate browsers may result in reduced functionality.

2023 Annual Emissions Reporting Notice (January 12, 2024)

Title V sources are expected to submit an electronic emissions statement annually. Emission statements must be submitted by March 1st of each year.

EMIT Guidance Documents:

Content Last Updated: January 24, 2024