Frequently Asked Questions

Does My Facility Require an Air Emission License?

Air emission licenses are issued to various commercial, industrial, and utility facilities that emit criteria air pollutants including PM, SO 2 , NOx, CO, VOCs, and HAPs

The following are exempt from licensing:

Fuel-burning equipment (or combination thereof), whose total maximum design heat input is less than 10.0 million British Thermal Units per hour. Fuel-burning equipment, excluding stationary internal combustion engines, less than 1.0 MMBtu/hr shall not be included in this threshold assessment and stationary internal combustion engines less than 0.5 MMBtu/hr shall not be included in this threshold assessment;

Stationary internal combustion engine (SICE) (or combination thereof) whose total maximum design heat input is less than 5.0 million British Thermal Units per hour or a gas/propane fired SICE (or combination) with a total maximum design heat input of less than 10.0 MMBtu/hr which demonstrates that the maximum design capacity is physically limited to generate 25 tons/year or less. Units less than 0.5 MMBtu/hr shall not be included in this threshold assessment;

Total facility general process sources whose emissions, without consideration of air pollution control apparatus and under normal operation, are less than 100 lb/day or 10 lb/hr of any regulated pollutant, except that these numerical limitations may not apply to a source which is subject to regulation of the control of hazardous air pollutants pursuant to Title 38 MRSA Section 545-B, New Source Performance Standards promulgated at 40 CFR Part 60, or National Emission Standards for Hazardous Air Pollutants (NESHAPS) promulgated at 40 CFR Part 61;

Please refer to Maine DEP Regulations Chapter 115 (licensing for minor sources) and Chapter 140 (licensing for major sources) for a detailed applicability determination. A complete list of licensing exemptions can be found in Chapter 115, Section (1)(C).

Who Must Apply for an Air Emission License?

Both Minor and Major sources must apply for air emission licenses. Examples of industries that may need to apply for an air emission license include: crematories, vet incinerators, rock crushers, asphalt batch plants, concrete batch plants, boat manufacturing, wood products manufacturing, pulp and paper mills, sawmills, tanneries, gas terminals, and metal or wood coating facilities.

What is a Minor Source?

Sources subject to Chapter 115 include facilities with the Potential to Emit less than the following:

50 ton per year VOC
10 ton per year of a single Hazardous Air Pollutant
25 ton per year of all Hazardous Air pollutants combined
100 ton per year of any other regulated pollutant

What is a Major Source?

Facilities with the Potential to Emit one or more of the following are major sources subject to Chapter 140:

50 ton per year VOC
10 ton per year of a single Hazardous Air Pollutant
25 ton per year of all Hazardous Air Pollutants combined
100 ton per year of any other regulated pollutant

Facilities with the potential to be subject to Chapter 140 but request to take a facility limit to avoid being regulated under Chapter 140 will require under Chapter 115.

What is a Best Practical Treatment?

Best Practical Treatment (BPT) means that method which controls or reduces emissions of regulated pollutants to the lowest possible level considering:

The then existing state of technology,
The effectiveness of available alternatives for reducing emissions from the source being considered, and
The economic feasibility for the type of establishment involved.

What is BACT and when is a BACT Analysis Required?

Best Available Control Technology (BACT) means an emission limitation based on the maximum degree of reduction for each emitted pollutant from new or modified emission units. A BACT analysis is reviewed on a case-by-case basis taking into account energy, environmental, and economic impacts. See Chapter 100 of the Department's regulations for a more explicit definition.

A BACT analysis is required for new sources and for both minor and major modifications to sources.

What criteria must a source meet to be issued a license?

Licenses are issued to sources when sources demonstrate that they meet the following state statutory requirements: emissions are receiving Best Practical Treatment; emissions will not violate applicable emission standards; and emissions will not violate ambient air quality standards in conjunction with emissions from other sources.

Is air emission modeling required?

Air emission modeling is usded to demonstrate compliance with ambient air quality standards.

Except for sources near Class I areas, an area where limited air quality is available, or other extenuating circumstances, source which emit less than the following are exempt from modeling:

50 tons per year (tpy) for SO2;
250 tpy for CO;
25 tpy for PM10 or TSP;
100 tpy for NOx;
0.6 tpy for lead; or
0.2 tpy of total chromium

How long are licenses in effect?

Licenses are in effect for five years unless otherwise stated in the license. If modifications to the gacility require that an amendment be issued, the term of the amendment is concurrent with the current license. Licenses must be renewed at the end of the five year period.

What is the application fee?

There is no application fee for existing licensed sources. Maine's air emission fee system is based on an annual fee charged to the facility based on licensed emissions. Any new source is responsible for submitting the annual fee with the initial application.

Whare are offsets required in Maine?

Offsetts are required when major new sources and existing sources with major modifications result in significant emissions or a significant emission increase in a nonattainment area. Please refer to Chapter 113 of the Department's regulations.

Nonattainment areas where NOx offsets are required in Maine include York, Cumberland, Androscoggin, Kennebec, Sagadahoc, Lincoln, and Knox County.

VOC offsets are required across the entire state of Maine.

Licensing

Frequently Asked Questions