Air Pollution Control Program

State Implementation Plan

There are six different criteria pollutants for which the U.S. Environmental Protection Agency, or EPA, is required to set National Ambient Air Quality Standards, or NAAQS.  EPA is also required to review each national air standard every five years to determine if the current standard is still adequate to protect public health, or if it should be revised.

After EPA revises or sets a new standard for a criteria pollutant, the boundary designation process begins. States submit boundary recommendations to EPA.  The boundary designation submittals for all criteria pollutants are available online.  After reviewing these recommendations, EPA designates areas across the country as either nonattainment or attainment/unclassifiable based on air quality monitoring or modeling data.  If an area is designated as nonattainment for a certain national ambient air quality standard it means the area either is not meeting the standard or is significantly contributing to an area not meeting the standard. Missouri’s State Implementation Plan, or SIP, is a compilation of all rules, regulations and documents giving the state authority to implement, enforce, attain, maintain and demonstrate compliance for each standard as required under the Clean Air Act. All SIPs are required to go through public comment periods and if adopted by the Missouri Air Conservation Commission, they are submitted to EPA for adoption in the federally approved SIP. If EPA adopts the plan submission, the SIP becomes federally enforceable.  A summary of Missouri’s federally approved SIP is available on EPA's website, and Missouri's approved SIP is also codified at 40 CFR 52 Subpart AA. Every time a NAAQS is revised the state is required to submit a SIP revision to EPA.

Types of SIPs

Every time an air standard is revised, the state is required to submit a SIP. For attainment/unclassifiable areas, the state is required to submit an infrastructure SIP that demonstrates the state’s authority to implement and enforce the standard and demonstrate that compliance with the standard will continue to be maintained. For nonattainment areas, the state is required to submit several different documents as part of the SIP for these areas under each standard in which the area has been designated nonattainment. 

The scope of the different SIP submittals required for each nonattainment area depends on the severity of the nonattainment area and the pollutant for which the area has been designated nonattainment. 

Nonattainment areas are usually required to submit an attainment demonstration SIP.  This portion of the SIP lays out all of the control strategies required to demonstrate the nonattainment area will meet the new standard by a certain date, known as the attainment date. Nonattainment area plans also typically require submission of a comprehensive emission inventory, a demonstration that reasonably available control measures have been implemented, and a demonstration that reasonable further progress goals will be achieved. Finally, once an area that has been designated as a non-attainment area has monitored pollutant levels in compliance with the standard for an extended period, then the area can submit a maintenance plan and be redesignated to maintenance area. The maintenance plan must demonstrate how the area will continue to maintain compliance with the standard for 10 years after attainment has been reached.

This web page shows the more recent SIPs submissions the state has made to EPA. Some submissions have been federally approved, while others are still pending EPA approval. SIP elements are revised from time to time, and the more recent revisions to SIPs are also listed on this website.

Ozone | Particulate Matter | Lead | Carbon Monoxide
Nitrogen Dioxide | Sulfur Dioxide | Regional Haze | Interstate Transport
Administrative | 111(d) | Air Quality Management Plan (AQMP)

Ozone

The first ozone NAAQS was published in 1979. The standard was based on one-hour average concentrations.  In 1997, EPA revised the ozone NAAQS and the new standard was based on a design value stemming from 8-hour average concentrations. In 2008, EPA again revised the ozone standard. The 2008 standard is lower than the 1997 standard, but still based on a design value stemming from 8-hour average concentrations. More information is available on the department's Ozone Information web page.

2008 8-hr O3 Standard: 75 parts per billion, or ppb

On Sept. 22, 2011, the U.S. Environmental Protection Agency released a memorandum to clarify for states the status of the 2008 Ozone National Ambient Air Quality Standard. In this document, EPA explicitly stated that the current standard is 0.075 parts per million, or 75 parts per billion.  This standard is based on a three year design value, which is calculated by taking the fourth highest daily high 8-hour average concentration recorded each year, for three years, and averaging the three years together.

St. Louis Area

Infrastructure SIP

1997 8-hr O3 Standard: 80 ppb

This standard was published by EPA in 1997, but litigated in the courts until 2004. This standard is based on a three year design value, which is calculated by taking the fourth highest daily high 8-hour average concentration recorded each year, for three years, and averaging the three years together. Due to rounding conventions, compliance with this standard is considered to be met when the highest monitored design value in an area is below 85 ppb.

St. Louis Area

Kansas City Area

Infrastructure SIP

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1979 1-hr O3 Standard: 120 ppb

This standard was revoked when the 8-hour ozone standard was published in 1997. While the standard is revoked, the control strategies developed to address this standard are still in effect unless they have been replaced by more stringent control strategies. Compliance with this standard was met when monitored ozone values reflected that no more than one expected exceedance would occur annually.

St. Louis Area

Kansas City Area

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Inspection and Maintenance SIPs

When new or revised NAAQS are published the EPA also releases implementation requirements for those new standards that must be included in SIPs. The Inspection/Maintenance Program, or I/M, is required by ozone implementation rules for all moderate ozone non-attainment areas.  This SIP defines the passenger vehicle emission inspection requirements for vehicles registered within the St. Louis ozone non-attainment area. More information is available on the Gateway Vehicle Inspection Program web page.

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Particulate Matter

Particulate matter is divided into two different groups based on the health effects of smaller sized particles. Fine particles are those particles smaller than 2.5 microns in size, or PM2.5. Coarse particles are those particles smaller than10 microns in size, or PM10. More information is available on the department's Fine Particulate Matter web page.

PM2.5

2012 PM2.5 Standard: Annual Standard: 12 µg/m3; 24-hr Standard: 35 µg/m3.

In December 2012, EPA promulgated a revised standard for PM2.5. The revision lowered the annual standard to 12 µg/m3 and is based on the 3 year average of the annual arithmetic mean.  The 24-hour standard was retained in 2012 and is based on a three year design value, which is calculated by taking the 98th percentile of the daily high 24-hour average concentrations recorded each year, for three years, and averaging the three years together.  The state developed boundary designation recommendations under the revised annual standard and submitted the recommendations to EPA in December 2013.  Click Here for a link to the NAAQS Boundary Designations Page.

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2006 PM2.5 Standard: Annual Standard: 15 µg/m3; 24-hr Standard: 35 µg/m3.

Compliance with the annual standard is based on the 3 year average of the annual arithmetic mean. The 24-hour standard is based on a three year design value, which is calculated by taking the 98th percentile of the daily high 24-hour average concentrations recorded each year, for three years, and averaging the three years together.

Infrastructure SIP

1997 PM2.5 Standard: Annual Standard: 15 µg/m3; 24-hour standard: 65 µg/m3.

Compliance with the annual standard is based on the three year average of the annual arithmetic mean. The 24-hour standard is based on a three year design value, which is calculated by taking the 98th percentile of the daily high 24-hour average concentrations recorded each year, for three years, and averaging the three years together.

St. Louis Area

Infrastructure SIP

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PM10

2006 24-hr PM10 Standard: 150 µg/m3

The 24-hour PM10 standard was unchanged in 2006. This standard is violated if the three-year average of the highest 24-hour concentration each year exceeds 150 micrograms/cubic meter. The 2006 revision also revoked the annual PM10 standard.

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Lead

Additional information, including health effects and air monitoring of lead is available on the department's Airborne Lead web page.

2008 Standard: 0.15 µg/m3

Buick

EPA revised the Lead NAAQS in 2008, lowering the standard to 1/10th of the level of the standard that was established in 1978.  In revising the standard, EPA also changed the form of the standard from an average over a 3-month calendar quarter to a rolling three-month average.

Attainment Demonstration for the 2008 Lead National Ambient Air Quality Standard – Buick

Modification to the Attainment Demonstration for the 2008 Lead National Ambient Air Quality Standard- Buick
Consent Judgment Modification

Herculaneum area

Attainment Demonstration for the 2008 Lead National Ambient Air Quality Standard – Herculaneum
Consent Judgement

Exide Technologies - Canon Hollow Facility

2008 Lead National Ambient Air Quality Standard Compliance Plan – Exide

Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F

Infrastructure SIP

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1978 Standard: 1.5 µg/m3

Compliance with this standard is based on the average monitored values of a three month calendar quarter.

Herculaneum area

Glover area

Buick

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Carbon Monoxide

Additional information is available on EPA's Carbon Monoxide web page.

2011 Standard - 1-hour standard: 35 ppm; 8-hour standard: 9 ppm.

The 1-hour and 8-hour values for this standard were not changed in 2011. A violation of this standard occurs if either the 1-hour average or 8-hour average standards are exceeded more than once in a year.

St. Louis Area

1971 Limited Maintenance Plan for the St. Louis Nonclassifiable Maintenance Area for the 8-Hour Carbon Monoxide NAAQS  (MACC Adoption: March 2014) (Pending EPA Approval)

1971 Limited Maintenance Plan for the St. Louis Nonclassifiable Maintenance Area for the 8-Hour Carbon Monoxide NAAQS
Appendix A
Appendix B

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Nitrogen Dioxide, or NO2

Additional information is available on EPA's Nitrogen Dioxide web page.

2010 Standard: Annual Standard: 0.053 ppm; 1-hour standard: 100 ppb.

In 2010, EPA promulgated a revision to this NAAQS by establishing a new 1-hour standard and retaining the annual standard  The 1-hour standard is based on a three year design value, which is calculated by taking the 98th percentile of the daily high 1-hour average concentrations recorded each year, for three years, and averaging the three years together.  The annual standard is based on the annual arithmetic mean and is not to be exceeded.

Infrastructure SIP

Sulfur Dioxide, or SO2

Additional information is available on EPA’s Sulfur Dioxide Implementation web page and on the department's Sulfur Dioxide web page.

2010 Primary standard (1-hour average): 75 ppb.

In 2010, this standard was revised. The revised standard revoked the annual and 24-hour primary standards. Previous to the 2010 NAAQS revision, the entire state was designated as attainment or unclassifiable under the annual and 24-hour primary SO2 standards. Under this revised standard, monitored pollutant concentrations are used to designate nonattainment and attainment areas for the initial round of designations.  The state developed a revised boundary recommendation in April 2013, which can be found on the NAAQS Boundary Designations page.  The 2010 SO2 standard is based on a three year design value, which is calculated by taking the 99th percentile of the daily high 1-hour average concentrations recorded each year, for three years, and averaging the three years together.

Secondary standard (3-hour average): 500 ppb.

On April 3, 2012, EPA promulgated a final rule to retain the current secondary standard for SO2.  The entire state is currently designated as attainment or unclassifiable under this standard.

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Regional Haze Plan

All states were required by the Clean Air Act to submit Regional Haze SIPs in order to address visibility in Class I areas.  This SIP addresses pollutants that affect visibility, and also those that cause acid rain.

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Interstate Transport SIPs

Under Section 110(a)(2)(D)(i)(l) of the Clean Air Act, states are required to submit SIPs in order to demonstrate that emissions in their state do not have a significant impact on downwind states’ ability to meet or maintain the NAAQS for all criteria pollutants. Typically, ozone and particulate matter are the two criteria pollutants in which long range transport of pollutants and precursors can have a significant impact on downwind states.

Administrative SIPs

Section 128 of the federal Clean Air Act Amendments of 1990 asserts that each SIP shall contain provisions regarding conflicts of interest and providing for representation of the public interest by the applicable state board.  This plan demonstrates that Missouri meets the Section 128 requirements via the referencing of specific corresponding state statutes and regulations. 

Section 111(d) Plans

Section 111(d) of the federal Clean Air Act Amendments of 1990 requires states to set emissions performance standards for existing sources of noncriteria pollutants (i.e., a pollutant for which there is no national ambient air quality standard). Section 111(d) specifically directs that the process for setting such standards be similar to the State Implementation Plan process for criteria pollutants under Section 110.  States must adopt plans that establish standards of performance for existing sources and submit the plans to EPA for approval.

Air Quality Management Plan (AQMP)

In October of 2008, the Missouri Department of Natural Resources’ Air Pollution Control Program undertook a pilot project to develop and implement an air quality management plan or AQMP in the Missouri/Illinois bi-state St. Louis area.  Instead of the traditional single-pollutant approach to SIP development, the AQMP is intended to address multiple air quality issues, including criteria pollutants such as ozone and fine particulate matter as well as air toxics. This final technical report explains the process of developing and implementing the AQMP in the St. Louis area, identifies lessons learned throughout the process, and offers suggestions for moving forward in regards to multi-pollutant air quality planning strategies in Missouri and across the country.

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