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State Implementation Plan (SIP) and Attainment

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Environment, Great Lakes, and Energy

State Implementation Plan (SIP) and Attainment

States are responsible for developing plans and implementing programs to meet and maintain National Ambient Air Quality Standards (NAAQS). Areas that meet the national ambient air quality standard are considered to be in "attainment" while areas in which air pollution levels persistently exceed ambient air quality standards may be designated "nonattainment." When NAAQS are tightened to better protect public health, some areas previously considered attainment may be designated to nonattainment even though monitoring shows that air quality continues to improve.


Robert Irvine, Air Quality Division

Public Notice for Air Quality Rules and State Implementation Plans

EGLE's Air Quality Division (AQD) has portions of its State Implementation Plan and/or Air Pollution Control Rules open for comment from the public. The complete Michigan SIP is a cumulative record of hundreds of documents developed in phases and for various purposes over many years. As federal requirements change States must add to, delete from, or revise components in the SIP. The Michigan SIP contains rules, statutes, permits, consent orders, plans, emissions inventories and budgets. The plan also contains binding commitments to take future actions under specific circumstances: Michigan's Air Pollution Control Rules are made up of multiple "parts" each covering its own subject matter and/or pollutants, which often need updating. It's also possible the AQD needs to create new rules to address air quality issues in the state.

More information on any actions open for comment are in the AQD Public Notice web page by scrolling down to "Air Quality Rules and the State Implementation Plan (SIP)" or you can go directly to the SIP-related public notice announcements.

General Program Information

State Implementation Plan (SIP) and Attainment covers a wide range of functions related to air quality control, including:

  • SIP development
  • national and state policy development
  • development of rules and regulations to attain and maintain the National Ambient Air Quality Standards (NAAQS)
  • stationary source emissions summation, data calculation, and emission modeling
  • support for mobile source planning and NAAQS transportation conformity
  • technical evaluation and support for emissions trading programs

SIP Information

Michigan's SIP contains the regulations and other materials for meeting clean air standards and associated Federal Clean Air Act (FCAA) requirements. SIPs include:

  • state regulations that USEPA has approved
  • state-issued, USEPA-approved orders requiring pollution control at individual companies
  • planning documents such as area-specific compilations of emissions estimates and computer simulations (modeling analyses) demonstrating that the regulatory limits assure that the air will meet air quality standards
  • general description of SIP types

In rare cases, federally promulgated regulations designated as Federal Implementation Plans (FIPs) are created in the place of SIPs. Although not actually SIPs, they are closely related.

Information by Pollutant

  • Carbon monoxide is produced primarily from transportation, fuel burning for space heating, and electrical generation. Industrial processes -- as well as wood, agricultural, and refuse burning -- also contribute to emissions of carbon monoxide. Carbon monoxide can exert toxic effects on humans by limiting oxygen distribution to organs and tissues. People with impaired circulatory systems are more vulnerable at lower levels than healthy individuals. Exposure to carbon monoxide can impair visual perception, work capacity, manual dexterity, learning ability, and the performance of complex tasks.

    Statewide annual carbon monoxide levels over the last decade generally have remained at one-third of the standard. A peak in the statewide average level during 1994 was due to two exceedances of the standard at one air monitoring site in Detroit. No exceedances of either 1-hour or 8-hour carbon monoxide standards have occurred in the last ten years. All areas in Michigan have been in attainment with the 1-hour and 8-hour standards since August 30, 1999.

  • The most common sources of lead (Pb) emissions are gasoline additives, non-ferrous smelting plants, and battery manufacturing. Historically, lead was added to gasoline as an additive to prevent engine knocking. The lead content of gasoline began to be controlled in the 1970s when legislation was introduced to gradually reduce lead levels. Currently, smelters and battery plants are the major sources of lead nationwide. Human exposure to lead can occur through ingestion or inhalation. The nervous system is most sensitive to the effects of lead and high exposures to lead can result in behavioral and learning disorders. Lead also may be a factor in high blood pressure and heart disease.

    Concentrations of lead in the air decreased steadily in the 1980s after the removal of lead from gasoline. On October 15, 2008, USEPA revised the national ambient air quality Standards (NAAQS) from 1.5 micrograms per cubic meter (µg/m3) to 0.15 µg/m3.  On November 22, 2011, the USEPA designated all areas of Michigan as unclassifiable / attainment for the 2008 lead NAAQS, with the exception of a part of the City of Belding. This area was designated attainment on May 31, 2017.

  • Mercury (chemical symbol Hg) is a heavy, silvery-white metal sometimes called quicksilver. It is the only metal that is liquid at ordinary temperatures and is naturally found in rocks and other environmental media. It has been historically released to the environment by natural events like volcanic eruptions and weathering of minerals. However, human and industrial activities, including those that use mercury directly or burn mercury bearing fossil fuels like coal, have increased the amount of mercury in the environment. Mercury is a persistent, bioaccumulative neurotoxin. Studies indicate an increased risk to a developing fetus upon exposure to methylmercury via maternal fish consumption. Mercury released from anthropogenic (man-made) and natural sources can be deposited in the environment, a portion of which is converted to methylmercury in aquatic systems before finding its way into fish.

    EGLE developed new air pollution control rules addressing mercury emissions from coal-fired electric generating units (EGUs), to meet the requirements of Governor Jennifer M. Granholm's directive to reduce mercury emission from coal-fired EGUs. The rules under Part 15 "Emission Limitations and Prohibitions - Mercury" went into effect October 16, 2009.  EGLE also revised the Parts 10 and 11 rules to address necessary changes to the testing/sampling and monitoring protocols.

    The Department revised the applicability of the rules in 2013 to be more in line with the Mercury and Air Toxics Standards (MATS). Part 15 will not be in effect as long as MATS is an applicable requirement regulating the emissions of mercury even though there have been legal challenges filed against MATS. However, once all legal challenges against MATS have been resolved which no further appeal or review is taken or available, one of two things will happen:

    1. If the provisions of MATS are upheld, Part 15 will be repealed and voided 60 days after the final judgment or order is issued; or
    2. If the provisions of MATS are struck down, Part 15 will be in force and go into effect three (3) calendar months after the termination of MATS.

    Access to all approved rules: Michigan Air Pollution Control Rules.

    Mercury Strategy Staff Report

    On January 30, 2008, a team of EGLE (then MDEQ) staff from the air, water, pollution prevention, and remediation programs, called the MDEQ Mercury Strategy Workgroup (MSWG), released their report entitled, MDEQ Mercury Strategy Staff Report along with its Appendices. The "MSWG Staff Report" was drafted in response to a charge from MDEQ Director to develop a strategy that eliminates anthropogenic or human mercury use and release to Michigan's environment. This comprehensive mercury report includes 67 recommendations, along with the workgroup's top ten priority actions identified. The desired outcome is to make Michigan's fish safe to eat. Getting there involves working cooperatively with a multitude of stakeholders. A copy of the MSWG Strategy's Executive Summary, which includes the 67 recommendations, is also available.

    Other Reports

    Additional Information




  • Nitrogen dioxide (NO2) is formed during combustion processes that create extremely high temperatures such as those that result from burning coal, oil, and gas fuels, and from burning fuels in motor vehicle engines. Nitrogen oxides (NOx) are necessary for the formation of ground level ozone and can contribute to acid rain. The human respiratory system is susceptible to effects caused by exposure to nitrogen dioxide. Asthmatics are particularly sensitive to these effects.

    Monitoring results show that ambient nitrogen dioxide levels have remained near the 0.02 parts per million (ppm) level since 1992, which is less than one-half of the standard. Michigan has never recorded a violation of the nitrogen dioxide standard. Michigan has been in attainment for nitrogen dioxide since March 3, 1978.



  • If you are looking for information specifically about ozone nonattainment workgroups, studies, and planning, check out the

    Ozone Nonattainment web page.

    • Ozone is an air pollutant formed from the mixing of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the air.
    • Things like gasoline, paints, and cleaning products can evaporate easily into the air and contain VOCs. NOx is created when fuel is burned.
    • On warm sunny days, ozone is formed when VOCs and NOx in the air meet and react with each other.

    The Ozone layer is the upper atmosphere helps protect the earth from the sun's harmful ultraviolet rays. Ground-level ozone is unhealthy to breathe. It can narrow a person's airways and lungs to work harder to provide oxygen to the body. Individuals most susceptible to the effects of ozone exposure include individuals with a pre-existing or chronic respiratory disease, children, and adults who actively exercise or work outdoors.

    For more questions and answers, check out our Ozone and Nonattainment FAQs.

    Other Resources



  • Particulate matter consists of solid particles, fine liquid droplets, or condensed liquids adsorbed onto solid particles. Particulate with a diameter of less than 10 micrometers in diameter is referred to as PM10 whereas very fine particles equal to or less than 2.5 micrometers in diameter is referred to as PM2.5.

    Particulate emissions are primarily composed of smoke, dust, dirt, soot, fly ash, and condensing vapors. The particles or droplets are composed of different elements depending on the emission source. Chemical reactions can occur in the atmosphere and form new chemical compounds or change the form from gases and liquids into solid particles. Industrial processes that cause these emissions include combustion, incineration, construction, mining, metal smelting, metal processing, and grinding. Non-industrial sources include motor vehicle exhaust, road dust, wind-blown soil, forest fires, volcanic activity, and farm operations.

    Particulate matter can affect breathing and the defenses of the lungs and aggravates existing respiratory and heart disease. More serious effects may occur depending on the length of exposure, the concentration, and the chemical nature of the particulate matter. Asthmatics and individuals with chronic lung and/or heart disease, people with influenza, the elderly, and children are the most susceptible. Fine particulate is especially problematic because it can penetrate deep into the lungs and remain there. PM2.5 is composed mainly of ammonium sulfate, ammonium nitrate, organic carbon, and smaller portions from elemental carbon and soil or crustal elements. PM2.5 comes from a variety of sources included burning, fugitive dust, and biogenic sources (from plants). PM2.5 can be emitted directly (primary) or react in the air to form particles (secondary).

    Additionally, particulate matter is the major cause of reduced visibility in many parts of the United States. PM2.5 is considered to be an important visibility-reducing component of urban and regional haze. Airborne particles can also impact vegetation and ecosystems and can cause damage to paints, building materials and/or surfaces. Deposition of acid aerosols and salts may increase corrosion of metals and impact plant tissue by corroding leaf surfaces and interfering with plant metabolism.

    PM NAAQS and Michigan

    The current primary (health-based) and secondary (welfare-based) standards for PM2.5 and PM10 are as documented in the table below.

    Standard Averaging Time Primary / Secondary

    Level in micrograms
    per cubic meter (µg/m3)

    PM2.5 Annual Primary


    Annual arithmetic mean, averaged over 3 years
    PM2.5 Annual Secondary


    Annual arithmetic mean, averaged over 3 years
    PM2.5 24-hour Primary and Secondary


    98th percentile, average over 3 years
    PM10 24-hour Primary and Secondary


    Not to be exceeded more than once per year on average over a 3-year period


    The PM10 primary and secondary 24-hour average levels over the decade have remained at nearly one-half of the standard. Michigan has been designated as being in attainment with the PM10 particulate National Ambient Air Quality Standard (NAAQS) since October 4, 1996. The primary and secondary 24-hour PM10 standard is 150 µg/m3, as documented in the table above.


    The PM2.5 primary/secondary annual and 24-hour average levels are documented in the table above. Under the Clean Air Act, those areas that violate the NAAQS, or are nearby and contribute to a violation, are considered "nonattainment."

    In 2006, USEPA maintained the PM2.5 annual standard at 15 µg/m3 and revised the NAAQS PM2.5 24-hour by reducing it to 35 µg/m3. USEPA designated seven counties in the Detroit-Ann Arbor Metropolitan Statistical Area (Southeast Michigan) as nonattainment for the annual and 24-hour PM2.5 NAAQS: Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne counties. Air quality monitoring data collected in the 2007 - 2010 period showed all seven counties in Southeast Michigan in attainment for the PM2.5 annual and daily NAAQS. In 2012, USEPA lowered the secondary annual PM2.5 standard from 15 µg/m3 to 12 µg/m3. All areas in Michigan were designated as “unclassifiable/attainment” associated with the 2012 PM2.5 revision. In 2020, USEPA retained the primary and secondary standards without revisions.

    In February 2024, USEPA revised the primary annual PM2.5 standard from 12 µg/m3 to 9 µg/m3. To meet the new annual standard a revision to the State Implementation Plan (SIP) will be developed and submitted to USEPA. The SIP revision will include emission reduction measures required by the federal Clean Air Act, including new rules to reduce emissions that contribute to PM2.5 pollution. Within two years of promulgation USEPA will issue designations (attainment, non-attainment, or unclassifiable). A timeline associated with work to be completed is included.

  • The United States Environmental Protection Agency (USEPA) revised the primary National Ambient Air Quality Standard (NAAQS) for sulfur dioxide (SO2) on June 2, 2010. The new short-term standard is based on the three-year average of the 99th percentile of the yearly distribution of one-hour daily maximum concentrations. This level was set at 75 parts per billion (ppb). The designations for the new one-hour SO2 standard were performed in three rounds.

    Round One

    The designations for Round One covered areas which, based on certified ambient air quality monitoring data for the years 2009-2011, showed violations of the one-hour SO2 standard. That standard was not being met at the Michigan Department of Environment, Great Lakes, and Energy (EGLE) monitoring station located at Southwestern High School in Detroit. Consequently, in July 2013, the USEPA formally designated a portion of southern Wayne County as "nonattainment" with the SO2 standard. This formal designation required EGLE to develop an air pollution abatement State Implementation Plan (SIP).

    On May 31, 2016, EGLE submitted its SO2 SIP strategy for southern Wayne County to the USEPA for final approval. This SIP is the strategy for bringing the area into compliance with the health-based NAAQS for SO2.

    Our strategy requires substantial SO2 reductions from two DTE coal-fired power plants and a U.S. Steel facility. In addition, Carmeuse Lime will be required to increase the height of their smokestack to lessen ground level impacts. DTE and Carmeuse Lime committed to controlling their SO2 emissions by modifying their existing air use permits. We developed State Rule 430 to make sure reductions from U.S. Steel are permanent and enforceable.

    The May 31, 2016, SIP submittal contained the draft version of Rule 430. The Rule became final on June 14, 2016. An addendum to the strategy, containing final Rule 430 and related updates, was submitted to the USEPA on June 30, 2016.

    Concurrent with the development of this abatement SIP, our air monitoring station at Southwestern High School came into compliance with the 75 ppb NAAQS. While air quality in the area has obviously improved, computer modeling of strategies within our plan is needed to demonstrate compliance with the NAAQS for those areas within the nonattainment area where we do not have air monitoring stations. Such modeling continued to show nonattainment.

    Later in the summer of 2016, US Steel filed a lawsuit alleging that Rule 430 was unconstitutional because it singled out the company for control. In the fall of 2017, a Court of Claims judgment was made agreeing with US Steel, disallowing Rule 430. Without the rule, the SIP did not demonstrate attainment of the NAAQS, and USEPA would not be able to approve it. This resulted in USEPA pursing a Federal Implementation Plan for the nonattainment area. This action is still underway.

    Round Two

    The designations in Round Two covered stationary sources that emitted more than 16,000 tons of SO2 in 2012 or emitted more than 2,600 tons of SO2, has a 2012 emission rate of at least 0.45 pounds (lbs) SO2 per million BTU (mmbtu), and that had not been announced (as of March 2, 2015) for retirement. USEPA identified eight coal-fired power plants which meet this criteria. EGLE proceeded with a designation analysis for these facilities and this information was submitted to the USEPA.

    On July 1, 2016, the USEPA confirmed that six counties containing large, coal-fired power plants are in attainment of the federal NAAQS for SO2 based on EGLE's computer modeling. The counties are Bay, Eaton, Ingham, Marquette, Monroe, and Ottawa.

    On July 1, 2016, the USEPA also confirmed that the air in southeastern St. Clair County exceeds the NAAQS for SO2. The finding, based on EGLE's computer modeling and recommendation, designated the southeastern portion of the county as nonattainment with the Clean Air Act's NAAQS for SO2. To address this public health concern, EGLE was required to develop a SIP by March 12, 2018 to lower SO2 air pollution in the county. The plan must require SO2 reductions in the area sufficient to attain the NAAQS within five years, and sooner if possible.

    EGLE's modeling shows the emissions from two coal-fired power plants, DTE Belle River and DTE St. Clair, are causing SO2 levels that exceed the new one-hour standard. EGLE worked with DTE to develop a SIP that would reduce SO2 emissions to protect public health and bring the area's air into compliance with the federal standard. DTE announced that the St. Clair power plant will cease operating in 2022, which is expected to lower SO2 levels such that the NAAQS may be met.

    Desiring to better understand the quality of the air in the vicinity of their two power plants, DTE installed and operated two SO2 air monitors in the vicinity of the two power plants since November 2016. The monitoring data has consistently shown SO2 levels in the area to be below the SO2 NAAQS. The Clean Air Act allows a state to submit to USEPA a Clean Data Determination (CDD) if air monitors show three consecutive years of attaining data in a nonattainment area. This action waives the requirement for a state to produce a SIP for the nonattainment area.

    EGLE determined that the CDD criteria have been met for the St Clair nonattainment area and submitted a CDD to USEPA in July 2020, waiving the SIP requirement for the area. Upon shutdown of the St Clair power plant in 2022, EGLE expects to submit a redesignation request to USEPA for the St. Clair county nonattainment area. As required, the request will include both monitoring data and modeling showing the area to be in attainment of the NAAQS.

    Round Three

    The Round Three designations affect stationary sources subject to the USEPA Data Requirements Rule (DRR). Under this rule, designations are required for areas having sources that emit more than 2,000 tons per year of SO2, and were not addressed in previous rounds. Two facilities were identified as falling within the emissions levels referenced in the DRR. The EGLE designation analysis for these two facilities showed impacts are meeting the NAAQS for SO2 based on computer modeling. EGLE submitted its designation recommendations and supporting documents of this analysis to the USEPA in January and February, 2017. The USEPA must designate these areas by December 31, 2017.

Other SIP-Related Programs

  • Acid Rain

    Information on the Acid Rain program is available via the Michigan Air Permit System.

    Emission Trading

    Federally mandated clean air market programs include various market-based regulatory programs designed to improve air quality by reducing outdoor concentrations of fine particles, sulfur dioxide, and nitrogen oxides. The Federal Clean Air Rules are a suite of actions intended to dramatically improve America's air quality. These rules specifically address the transport of pollution across state borders. These rules provide national tools to achieve significant improvement in air quality and the associated benefits of improved health, longevity, and quality of life for all Americans.

    Good Neighbor Plan (GNP) and Cross-State Air Pollution Rule (CSAPR)

    The Good Neighbor Plan (GNP) is the newest iteration of regulations made to address interstate transport.  GNP includes the CSAPR program, which focuses specifically on Electrical Generating Units (EGUs), as well as NOx emissions control requirements for certain emission units in nine industrial categories.  More information about these programs is available via the CSAPR webpage.

    NOx SIP Call

    The NOx SIP Call is an early interstate transport regulation affecting EGUs and larger non-EGU NOx sources during the ozone season (May 1 through September 30).  The larger non-EGU NOx sources that are not subject to CSAPR or GNP are still subject to this rule.  Michigan Administrative Air Pollution Control Rule 810 addresses this subset of sources.

    Clean Air Market Programs

    Federally mandated clean air market programs (i.e. cap and trade) include various market-based regulatory programs designed to improve air quality by reducing outdoor concentrations of fine particles, sulfur dioxide, nitrogen oxides, and mercury.

    The Federal Clean Air Rules are a suite of actions intended to dramatically improve America's air quality. These rules specifically address the transport of pollution across state borders (i.e. including the Clean Air Interstate Rule and the Clean Air Mercury Rules). These rules provide national tools to achieve significant improvement in air quality and the associated benefits of improved health, longevity and quality of life for all Americans. Taken together, they will make the next 15 years one of the most productive periods of air quality improvement in America's history.

    Michigan had submitted rules to the USEPA as part of the Michigan State Implementation Plan (SIP) to address these federal mandates.

  • Greenhouse gases (GHGs) are produced in a wide variety of ways, many of which occur in Michigan.

  • Mobile engines burn fuel and generate air pollution through combustion or evaporation that impacts the air we breathe. Key pollutants produced include carbon monoxide, hydrocarbons, nitrogen oxides, particulate matter, air toxics (including diesel exhaust), and greenhouse gases. The US government is responsible for regulating mobile sources. The Air Quality Division (AQD) encourages public awareness and promotes emission reductions through clean air choices.

    General Conformity

    General conformity applies to all federal actions including funding, licensing, permitting, and approval (except for FHWA/FTA projects defined in 40 CFR 93.101) in areas deemed non-attainment or maintenance for any of the NAAQS criteria pollutants (ozone, carbon monoxide, particulate matter, nitrogen dioxide, lead, and sulfur dioxide). For example, general conformity applies to the majority of airport activities (construction, additions) funded by federal monies. Like transportation conformity, general conformity ensures that actions slated for completion will not cause additional, worsen existing, or contribute to new violations of the NAAQS or lead to a delay in reaching attainment.

    Mobile Sources / Fuels



    U.S. Dept. of Energy

    Transportation Planning

    Under the 1990 Clean Air Act Amendments, the US Department of Transportation cannot fund, authorize, or approve federal actions to support programs or projects which are not first found to conform to the Clean Air Act requirements. Transportation conformity applies to transportation plans, transportation improvement programs, and projects funded or approved by Federal Highway Administration (FHWA) or Federal Transit Administration (FTA) in areas that do not meet National Ambient Air Quality Standards (NAAQS) (non-attainment areas) or have not met them in the past (maintenance areas). It ensures that federal funding and approval are awarded only to projects that attain the NAAQS for ozone, carbon monoxide, particulate matter, and nitrogen dioxide. The FHWA and the FTA jointly make transportation conformity determinations.

    The Congestion Mitigation and Air Quality Improvement (CMAQ) Program is jointly administered by the FHWA and FTA. It provides funding to state and local agencies, and to transportation planning organizations, to invest in projects that both contribute to air quality improvements and congestion relief. CMAQ is funded by the Moving Ahead for Progress in the 21st Century Act (MAP-21) signed into law in July 2012. The AQD is part of a collaborative effort along with MDOT, the USEPA, and the FHWA.

  • In July 1999, the US Environmental Protection Agency (USEPA) published regulations to address visibility impairment in our nation's largest national parks and wilderness (Class I) areas. This rule was commonly known as the "Regional Haze Rule" (64 Federal Register 35714 - July, 1999) and is found in 40 CFR Part 51, Sections 51.300 through 51.309. On July 6, 2005, USEPA published a revised final rule, including Appendix Y to 40 CFR part 51, "Guidelines for BART Determinations Under the Regional Haze Rule." Under the USEPA Regional Haze Rule, certain emission sources "that may reasonably be anticipated to cause or contribute" to visibility impairment in downwind Class I areas are required to install Best Available Retrofit Technology (BART). The rule also requires affected states to demonstrate reasonable progress towards reaching natural background conditions by 2064. The first progress goal is 2018.

    Within its boundary, Michigan has two Class I areas: Isle Royale National Park and Seney Wilderness Area. Michigan responded to the USEPA requirement and submitted a Regional Haze State Implementation Plan (SIP) in 2010.

    The second round of the Regional Haze program is underway and addresses the time period from 2018-2028. USEPA published an updated guidance document in 2019 that is available at the USEPA Regional Haze website. The Air Quality Division is in the process of identifying sources that may cause or contribute to visibility impairment in these areas and determining whether additional emission controls are necessary. The SIP must also include a demonstration of reasonable progress toward reaching the second incremental progress goal (2028) for each of the state's Class I areas. The SIP is scheduled to be completed and receive public comment in early 2021 and be submitted to USEPA in the summer of 2021.

  • The Clean Air Act Sections 129 and 111(d) allow Michigan to seek delegation of enforcement and implementation from USEPA over certain emission guidelines through approved State Plans. Michigan has created state plans or submitted negative declarations for the following sources: