Introduction to State Implementation Plan (SIP)

Select a question below to learn about the State Implementation Plan (SIP):

What is a SIP?

A State Implementation Plan (SIP) is an enforceable plan developed at the state level that explains how the state will comply with air quality standards according to the Federal Clean Air Act (CAA). A SIP must be submitted by the state government of any state that has areas that are designated in nonattainment of Federal air quality standards. In order to understand SIPs, you should understand the role of the following:

Federal Clean Air Act: The federal (CAA) is the legal foundation for the national air pollution control program. The CAA requires each state to produce and regularly update a SIP. The CAA also requires that SIPs include a description of control strategies, or requirements to deal with pollution, for areas that fail to achieve the national ambient air quality standards (NAAQS). Finally, the CAA grants powers of enforcement to the Environmental Protection Agency (EPA).
Environmental Protection Agency: The CAA grants the EPA power to establish national air quality standards, to approve or reject SIPs, to replace SIPs with Federal Implementation Plans (FIPs) when deemed necessary, and to monitor achievement of goals laid out in SIPs and FIPs.

Why are SIPs necessary?

SIPs protect the air : SIPs play a key role in attaining good air quality and protecting citizen's health.
SIPs are required by law : the federal Clean Air Act requires states with areas failing to comply with national ambient air quality standards to produce a SIP.
Failure to produce a SIP has consequences : if a state fails to submit or implement a SIP, or if it submits a SIP that is unacceptable to the EPA, the EPA has the power to impose sanctions or other penalties on that state.

Who is affected by SIPs?

As an individual: Protect your health : SIPs aim to implement air quality standards, which are created to protect human health, including your health. Therefore, SIPs aim to improve air quality to a degree that is beneficial for the health and well-being of you and your family.
As a business: Regulations : rules set requirements that may apply to your industry. Regulations may place restrictions on activities and equipment used in your business that affect quality levels. Other regulations may provide incentives that your firm may be able to take advantage of.
Regulations : Rules set requirements that may affect your everyday life. In some cases, rules may place restrictions on you by creating requirements that may affect the operation, design and emissions level of your property (i.e. your motor vehicle). In other cases rules may offer you incentives to choose technologies that further the SIP's goal.

What are the six criteria pollutants?

Ozone (O₃ ) is a gas composed of three oxygen atoms. It is not usually emitted directly into the air, but at ground -level is created by a chemical reaction between oxides of nitrogen (NO_x) and volatile organic compounds (VOC) in the presence of sunlight. Ozone has the same chemical structure whether it occurs miles above the earth or at ground-level and can be "good" or "bad," depending on its location in the atmosphere.
Particulate matter, also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets. Particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles. The size of particles is directly linked to their potential for causing health problems. EPA is concerned about particles that are 10 micrometers in diameter or smaller because those are the particles that generally pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects. EPA groups particle pollution into two categories:
1. "Inhalable coarse particles," such as those found near roadways and dusty industries, are larger than 2.5 micrometers and smaller than 10 micrometers in diameter.
2. "Fine particles," such as those found in smoke and haze, are 2.5 micrometers in diameter and smaller. These particles can be directly emitted from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.
Lead (Pb) 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. As a result of EPA's regulatory efforts to remove lead from gasoline, emissions of lead from the transportation sector dramatically declined by 95 percent between 1980 and 1999, and levels of lead in the air decreased by 94 percent between 1980 and 1999. Today, the highest levels of lead in air are usually found near lead smelters. Other stationary sources are waste incinerators, utilities, and lead-acid battery manufacturers.
Nitrogen dioxide (NO₂ ) is one of a group of highly reactive gasses known as "oxides of nitrogen," or "nitrogen oxides (NO_x )." Other nitrogen oxides include nitrous acid and nitric acid. While EPA's National Ambient Air Quality Standard covers this entire group of NO_x, NO₂ is the component of greatest interest and the indicator for the larger group of nitrogen oxides. NO₂ forms quickly from emissions from cars, trucks and buses, power plants, and off-road equipment. In addition to contributing to the formation of ground-level ozone, and fine particle pollution, NO₂ is linked with a number of adverse effects on the respiratory system.
Carbon monoxide , or CO, is a colorless, odorless gas that is formed when carbon in fuel is not burned completely. It is a component of motor vehicle exhaust, which contributes about 56 percent of all CO emissions nationwide. Other non-road engines and vehicles (such as construction equipment and boats) contribute about 22 percent of all CO emissions nationwide. Higher levels of CO generally occur in areas with heavy traffic congestion. In cities, 85 to 95 percent of all CO emissions may come from motor vehicle exhaust. Other sources of CO emissions include industrial processes (such as metals processing and chemical manufacturing), residential wood burning, and natural sources such as forest fires. Wood stoves, gas stoves, cigarette smoke, and unvented gas and kerosene space heaters are sources of CO indoors. The highest levels of CO in the outside air typically occur during the colder months of the year when inversion conditions are more frequent. The air pollution becomes trapped near the ground beneath a layer of warm air.
Sulfur dioxide (SO₂ ) is one of a group of highly reactive gasses known as "oxides of sulfur." The largest sources of SO₂ emissions are from fossil fuel combustion at power plants (66%) and other industrial facilities (29%). Smaller sources of SO₂ emissions include industrial processes such as extracting metal from ore, and the burning of high sulfur containing fuels by locomotives, large ships, and non-road equipment. SO₂ is linked with a number of adverse effects on the respiratory system.

What are the National Ambient Air Quality Standards (NAAQS)?

National Ambient Air Quality Standards

Pollutant	Primary Standards Level	Primary Standards Averaging Time	Secondary Standards Level	Secondary Standards Averaging Time
Carbon Monoxide	9ppm (10 µg/m³)	8-hour⁽¹⁾	none	none
Carbon Monoxide	35ppm (40 mg/m3)	1-hour ⁽¹⁾	none	none
Lead	0.15 µg/m³ ⁽²⁾	Rolling 3-Month Average	Same as Primary	Same as Primary
Lead	1.5 µg/m³	Quarterly Average	Same as Primary	Same as Primary
Nitrogen Dioxide	53 ppb ⁽³⁾	Annual (Arithmetic Average)	Same as Primary	Same as Primary
Nitrogen Dioxide	100 ppb	1-hour ⁽⁴⁾	Same as Primary	Same as Primary
Particulate Matter (PM₁₀)	150 µg/m³	24-hour ⁽⁵⁾	Same as Primary	Same as Primary
Particulate Matter (PM_2.5)	12 µg/m³	Annual ⁽⁶⁾ (Arithmetic Average)	Same as Primary	Same as Primary
Particulate Matter (PM_2.5)	35 µg/m³	24-hour ⁽⁷⁾	Same as Primary	Same as Primary
Ozone	0.075ppm (2008 std)	8-hour ⁽⁸⁾	Same as Primary	Same as Primary
Ozone	0.08ppm (1997 std)	8-hour ⁽⁹⁾	Same as Primary	Same as Primary
Ozone	0.12ppm	1-hour ⁽¹⁰⁾	Same as Primary	Same as Primary
Sulfur Dioxide	0.03ppm	Annual (Arithmetic Average)	0.5 ppm	3-hour ⁽¹⁾
Sulfur Dioxide	0.14ppm	24-hour ⁽¹⁾	0.5 ppm	3-hour ⁽¹⁾
Sulfur Dioxide	75 ppb ⁽¹¹⁾	1-hour ⁽¹⁾	None	None

(1) Not to be exceeded more than once per year.

(2) Final rule signed October 15, 2008.

(3) The official level of the annual NO2 standard is 0.053 ppm, equal to 53 ppb, which is shown here for the purpose of clearer comparison to the 1-hour standard.

(4) To attain this standard, the 3-year average of the 98th percentile of the daily maximum 1-hour average at each monitor within an area must not exceed 100 ppb (effective January 22, 2010).

(5) Not to be exceeded more than once per year on average over 3 years.

(6) To attain this standard, the 3-year average of the weighted annual mean PM_2.5 concentrations from single or multiple community-oriented monitors must not exceed 15.0 µg/m³.

(7) To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented monitor within an area must not exceed 35 µg/m³ (effective December 17, 2006).

(8) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.075 ppm (effective May 27, 2008).

(9) (a) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.08 ppm. (b) The 1997 standard—and the implementation rules for that standard—will remain in place for implementation purposes as EPA undertakes rule making to address the transition from the 1997 ozone standard to the 2008 ozone standard. (c) EPA is in the process of reconsidering these standards (set in March 2008).

(10) (a) EPA revoked the 1-hour ozone standard in all areas, although some areas have continuing obligations under that standard ("anti-backsliding"). (b) The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is ≤ 1.

(11) (a) Final rule signed June 2, 2010. To attain this standard, the 3-year average of the 99th percentile of the daily maximum 1-hour average at each monitor within an area must not exceed 75 ppb.

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