Who needs an air permit?

In Minnesota, air quality (AQ) operating permits are required for certain existing air emission facilities, and AQ construction permits may be required before beginning 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 standards are 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.

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.

Does my business need an air permit?

While there are number of reasons that an air permit may be required, facilities that have the potential to emit (PTE) any regulated pollutant in amounts greater than specific thresholds must obtain a total facility permit. Certain sources that have low actual emissions (as opposed to PTE) may qualify as a conditionally exempt source by complying with technical standards. Applicable rules and regulations must still be complied with as outlined in Minn. R. 7008.2000.

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): learn how to calculate PTE. 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 sometimes called “synthetic minor” limits; see the link at the bottom of this page for information on how to propose synthetic minor limits on PTE. These limits are then put into the facility's permit.

What is a regulated pollutant?

In general there are two types of regulated pollutants: New Source Review and hazardous air pollutants.

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, 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 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) 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 organic 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, 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. The NAAQS for particulate matter have been established based on the indicators PM10 and PM2.5.

In July 1987, EPA began using a new indicator, PM10, 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.

In July 1997, EPA added fine particles as an additional indicator. 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).

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 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.

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 them. More information on HAPS is available from these sources:

What are the operating permit thresholds?

There are both federal and state emission thresholds that trigger the need for an AQ operating permit.

If the total facility PTE for any of the regulated pollutants is greater than or equal to any federal threshold (under the “Federal” heading in the table below), the facility will need a Title V permit unless it can accept synthetic minor limits on its PTE to bring it below the federal thresholds. Some sources will need a Title V permit regardless of the potential emissions – see Minn. R. 7007.0200.

If the total facility PTE is less than all of the federal thresholds but is still greater than or equal to any of the state thresholds (shown under the “State” heading in the table below), or if a synthetic minor limit is proposed in order to avoid needing a Title V permit, the facility will need a state permit.

If the total facility PTE is less than both the federal and state thresholds (without any limits on its PTE) the facility may not need a permit unless it meets one of the criteria outlined in Minn. R. 7007.0250, but should keep records of its calculations.

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

Besides total facility operating permits, another 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 operating permit will not need a construction permit for a modification at its facility unless the PTE of the modified facility will be at or above one of the thresholds described above. A facility can also take limits to qualify for certain types of permit amendments.