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All about air permits

In Minnesota, air quality (AQ) permits are required to operate certain existing air emission facilities and to begin construction on either new facilities or modifications to existing facilities. Air quality permits contain a wide range of state and federal requirements to minimize the impact of the air emissions from these facilities on the environment. Some Federal programs involve performance standards for specific types of units or processes within a facility. Others have a wider scope and involve addressing the impact of newly constructed facilities, or modifications to existing facilities, on ambient air quality.

The 1990 amendments to the Clean Air Act involved many significant changes to the federal air quality programs which, in turn, caused a major overhaul of Minnesota's existing air permitting program. Two of the larger changes included the way hazardous air pollutants are addressed, and the addition of the Title V (or Part 70) operating permit program. Title V refers to the section of the Clean Air Act, and Part 70 refers to the part of Title 40 of the Code of Federal Regulations, where you will find the requirements for this program. Minnesota's air rules were revised in October 1993, in response to these changes. Companies who were required to apply for Title V operating permits had to submit their Title V permit applications to the MPCA between 1995 and 1996 (depending on the industry category).

NOTE: The following information is not meant to be a tool to determine applicable Federal and State regulations for a specific situation. The method of choice should always be a thorough review of the State and Federal rules and regulations.

Who needs a permit?

In general, facilities who have the potential to emit (also known as PTE) any regulated pollutant, in greater than specific threshold amounts, must obtain a total facility permit.

What does PTE mean?

PTE is defined as the maximum capacity of an emission unit or source to emit a pollutant under its physical and operational design while operating at the maximum number of hours (usually 8760 hours per year). In just about all cases, PTE calculations are based on the assumption that the facility operates at its maximum design capacity, 24 hours a day, 365 days a year (this equals 8,760 hours per year). Many times, a facility will take a limit on a unit (such as on the number of hours of operation or amount of material processed) to reduce its potential to emit so that it can avoid certain requirements that would otherwise have been applicable. These limits are then put into the facility's permit.

What is a regulated pollutant?

In general there are two types of regulated pollutants:

  1. New Source Review (NSR) pollutants -  the regulated NSR pollutants include the National Ambient Air Quality Standards (NAAQS) pollutants and some other pollutants including greenhouse gases, sulfuric acid mist, hydrogen sulfide, etc. Pollutants for which there are NAAQS are referred to as Criteria Pollutants. Criteria pollutants all have human health-based or welfare-based standards that set the maximum concentrations that are allowed in the ambient air (i.e., the air that the general public is exposed to). They include:

Nitrogen oxides (NO)

Nitrogen oxides, or NOx, is the generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts. Many of the nitrogen oxides are colorless and odorless. However, one common pollutant, nitrogen dioxide (NO2) along with particles in the air can often be seen as a reddish-brown layer over many urban areas. Nitrogen oxides form when fuel is burned at high temperatures, as in a combustion process. The primary sources of NOx are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels.

Sulfur dioxide (SO2)

Sulfur dioxide is a heavy, pungent, colorless gas formed primarily by the combustion of coal, oil, and diesel fuels. Elevated levels can impair breathing, lead to other respiratory symptoms, and at very high levels aggravate heart disease. People with asthma are most at risk. Sulfur dioxide also contributes to acid rain, which can damage plants, lakes and buildings.

Volatile organic compounds (VOC)

Volatile organic compounds (VOC) are a principal component in atmospheric reactions that form ozone and other photochemical oxidants. VOCs are emitted from diverse sources, including automobiles, chemical manufacturing facilities, drycleaners, paint shops and other commercial and residential sources that use solvent and paint. The term, volatile organic compound is defined in federal rules as a chemical that participates in forming ozone. Methane, a nonreactive compound is not a VOC, nor are other oganic chemicals with negligible photochemical reactivity. VOCs are emitted from transportation and industrial sources, such as automobile exhaust, gasoline/oil storage and transfer, chemical manufacturing, dry cleaners, paint shops and other facilities using solvents.

Particulate Matter (PM)

Particulate matter, or PM, is the term for particles found in the air, including dust, dirt, soot, smoke, and liquid droplets. Particles can be suspended in the air for long periods of time. Some particles are large or dark enough to be seen as soot or smoke. Others are so small that individually they can only be detected with an electron microscope. Some particles are directly emitted into the air. They come from a variety of sources such as cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood.

Particulate matter less than 10 microns in diameter (PM)

In July 1987, EPA began using a new indicator, PM-10, which includes only those particles with aerodynamic diameter smaller than 10 um. Ten microns is approximately one seventh the diameter of a human hair. This fraction of TSP is responsible for most of the adverse human health effects of particulate matter because of the particles' ability to reach the lower regions of the respiratory tract.

Particulate matter less than 2.5 microns in diameter (PM)

Fine particulate matter is a complex mixture of very small liquid droplets or solid particles in the air. Major sources are cars, trucks, construction equipment, coal-fired power plants, wood burning, vegetation and livestock. These particles can be directly released when coal, gasoline, diesel fuels and wood are burned. Many fine particles are also formed in the atmosphere from chemical reactions of nitrogen oxides, sulfur oxides, organic compounds and ammonia. Fine particulates are associated with increased hospitalizations and deaths due to respiratory and heart disease and can worsen the symptoms of asthma. People with respiratory or heart disease, the elderly and children are the groups most at risk. Fine particles are also major contributors to reduced visibility (haze).

Carbon monoxide (CO)

A colorless, toxic gas produced by incomplete burning of carbon-based fuels, including: gasoline, oil and wood. Carbon monoxide is also produced from incomplete combustion of many natural and synthetic products. For instance, cigarette smoke contains carbon monoxide. When carbon monoxide gets into the body, the carbon monoxide combines with chemicals in the blood and prevents the blood from bringing oxygen to cells, tissues and organs. The human body needs oxygen for energy, so high-level exposures to carbon monoxide can cause serious health effects, with death possible from massive exposures. Symptoms of carbon monoxide exposure include vision problems, reduced alertness, and general reduction in mental and physical functions. Carbon monoxide exposures are especially harmful to people with heart, lung and circulatory system diseases.

Lead (Pb)

Lead is a metal found naturally in the environment as well as in manufactured products. The major sources of lead emissions have historically been motor vehicles (such as cars and trucks) and industrial sources. Due to the phase out of leaded gasoline, metals processing is the major source of lead emissions to the air today. The highest levels of lead in air are generally found near lead smelters. Other stationary sources are waste incinerators, utilities, and lead-acid battery manufacturers. In the ambient air, lead exists primarily as inhalable-size particulate matter. Lead occurs naturally in small quantities in soil, water and air.

  1. Hazardous air pollutants (HAPs) - are defined by a list of chemicals that are known or suspected of causing cancer or other serious health effects, such as developmental effects or birth defects. There were originally 189 HAPs, but various rulemaking activities have removed and/or redefined some of the HAPs. More information is available from:

What are the thresholds?

There are both federal and state total facility thresholds. First, a facility calculates the PTE for each regulated pollutant, from each of its emission units. Then the total potential emissions for the whole facility, for each regulated pollutant are aggregated and compared to each of the federal thresholds. If the total facility PTE for any of the regulated pollutants is over any federal threshold, it will need a Title V permit unless it can accept limits on its PTE to bring it below the federal thresholds. If the facility's total potential emissions are less than the federal thresholds (or it accepts limits so that this is true) but are still greater than the state thresholds, the facility will need a state permit. If the facility's total emissions are less than the state thresholds (without any limits on its PTE) the facility does not need a permit, but should keep records of its calculations.

PollutantTotal facility PTE thresholds
(tons per year)
Federal State
NOx 100 100
SO2 100 50
VOC 100 100
PM 100 100
PM10 100 25
PM2.5 100 100
CO 100 100
Pb 10 0.5
CO2e 100,000 100,000
1 HAP 10 10
> 1 HAP 25 25
All other NSR pollutants 100 100

An important point to keep in mind is that even if a facility doesn't need a permit based on its PTE, it may still need one for other reasons. For example, two federal regulatory programs require some facilities to apply for permits regardless of how much air pollution they could potentially cause.

Besides total facility operating permits, another general class of permits that the MPCA issues are construction permits. Construction permits are issued for the construction of a new facility whose PTE is over the federal or state thresholds, or the modification of an existing facility. In general, a facility that doesn't already require a total facility permit will not need a construction permit for a modification at its facility unless the additional PTE of the construction activity increases the PTE of the total facility to the point that the PTE of the total facility crosses a permitting threshold. A facility can also take limits to qualify for certain types of permit amendments.

What types of total facility permits exist?

In general, the kind of permit a facility is required to apply for will depend on how much air pollution the facility could potentially cause based on the kinds of equipment or processes the facility operates. A table comparing features of various types of total facility permits is available below:


In general, "federal" is the term used to name those permits required specifically by federal regulations. These permits are required for the larger emitters of air pollutants. These permits programs are implemented nationwide under the same general principles and guidance. The EPA evaluates and approves state programs that serve to implement these federal requirements.

  • Individual Total Facility - Typically a facility requiring a federal-level permit must apply for an individual permit, which is written specifically for the activities (emission units, controls, etc.) at the facility and includes only those requirements applicable to the facility.
  • General - Two general permit options are currently available at the federal level. One is for general manufacturing facilities and the other is for fiberglass manufacturing facilities. Usually, because general permits are pre-written to cover a range of operating scenarios and applicable requirements, they require less processing by the MPCA. Because of this, a general permit may be quicker to obtain than an individual total facility permit, provided the specific qualifications are met.


In general, "state" is the term used to name those permits required by state rules and statutes. In Minnesota, these permits are the result of state specific strategies approved by the federal government to regulate minor sources of air emissions and to attain compliance with broader air quality federal laws and regulations.

  • Individual Total Facility – The individual total facility permit at the state level is very similar to the federal-level individual permit. However, at the state level, there are more alternatives to the individual permit available.
  • Registration- Registration permits are for facilities with low actual emissions (i.e., what actually comes out the stack) versus their potential emissions. In general, the facility's actual emissions must be less than 50 percent of the federal thresholds. There are other requirements. These permits are similar to general permits in that they are easier to obtain and the requirements are less rigorous when making modifications.
    • Registration Permit Fact Sheet (currently being updated)
    • Registration Permit Handbook (currently being updated)
  • Capped- The “capped emission permit” option is designed for noncomplex facilities that do not qualify for a registration permit and do require site-specific permit conditions. In general, the facility’s actual emissions must be less than 75 to 90% of the federal thresholds. These permits are quicker to obtain than an individual state permit and require less agency involvement when making modifications.
  • Environmental Management System (EMS)- This individually issued state permit option allows small and medium-sized air emission facilities that employ a qualifying (ISO 14001) EMS to operate under emission caps set typically set below 90 percent of federal thresholds. To provide a regulatory incentive to establish a qualifying EMS , the permit offers relief from minor and moderate permit amendment application requirements, and from some some recordkeeping and reporting requirements.
  • General- Similar to the federal general permits except that the PTE for these facilities are below the federal thresholds. One general permit option (non-metallic mineral processing) is currently available at the state level.

State permits generally do not expire. The US EPA requires that Title V permits be renewed every five years. All individual total facility permits must be put on public notice for 30 days. Federal individual total facility permits are also subject to a 45-day EPA review period before they can be issued, which in most cases will run concurrently with the 30-day public notice period. It can take anywhere from six months to a year or longer to issue individual total facility permits depending on the number of complicated issues involved.

What about modifications?

If a facility wants to make changes at its facility after receiving a total facility permit, it should first determine if it will need an amendment to its permit. Registration Permit and Capped Permits preauthorize modifications, provided the modified facility still qualifies for the same permit. To determine if its individual permit must be amended, the facility must: calculate the PTE of the modification, review the applicable state and federal rules and regulations, and determine the applicable amendment type (if one is necessary). These items should all be done before starting construction on the modification because some amendment types require that the permit amendment be issued before construction commences on the modification. The permit amendment types are differentiated based on threshold levels of emissions and/or the applicability of certain Federal programs. The types of amendments are: administrative, contravening permit terms, minor, moderate, major. Major amendments must be placed on public notice, can take as many as six months or more to issue, and generally involve the consideration of Federal programs and other changes that have the potential to significantly affect air quality.

How are permits processed?

The degree of involvement by the MPCA with a permit action depends on the type of permit. In general, the more significant the potential impact to air quality a permit or permit amendment has, the more detailed the involvement by MPCA staff. Individual total facility permits, and all amendments except administrative amendments go to permit teams made up of a permit writer/engineer and compliance and enforcement staff who work together with the facility to draft the permit.

How does the MPCA prioritize its permitting effort?

In general, the MPCA gives priority to facilities that need their permits to begin construction or operation of either a modification or a totally new facility.

  • Construction permits: Applications for permit amendments are put in a queue, to be worked on as staff become available. There is also an expedited permit program where facilities pay to have staff work overtime to draft their permit. This is only useful when the queue is large. Total facility operating permits for new (not yet constructed) facilities are also put in this queue.

  • Total Facility Operating permits: This includes reissuance of federal permits issued five or more years ago. These applications are worked on based on the priorities set by the AQ permit management. At this point in time, most facilities in Minnesota who require one have received their total facility operating permit. Those facilities with federal permits, which have a five-year expiration schedule, have begun applying for reissuance of those permits. While still keeping up with permits and amendments required for construction projects, the goal is to manage the reissuance of federal permits to minimize the backlog.


For assistance with air permits in Minnesota, contact the MPCA at 651-296-6300 or 800-657-3864 and ask for Business Assistance.

Last modified on October 22, 2014 13:40

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