2020-12136. Air Plan Approval; TN; Removal of the Vehicle I/M Program, Hamilton County, TN

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency (EPA) is proposing to approve a State Implementation Plan (SIP) revision submitted by the State of Tennessee, through the Tennessee Department of Environment and Conservation (TDEC), through a letter dated February 26, 2020. Specifically, EPA is proposing to approve the removal of Tennessee's inspection and maintenance (I/M) program requirements for Hamilton County from the federally approved SIP. EPA is proposing to approve the removal of the I/M program requirements for Hamilton County from the federally approved SIP because removing the requirements is consistent with the Clean Air Act (CAA or Act) and applicable regulations.

DATES:

Comments must be received on or before July 8, 2020.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R04-OAR-2019-0619 at http://www.regulations.gov. Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. EPA will generally not consider comments or comment contents located outside of the primary submission (i.e., on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit http://www.epa.gov/​dockets/​commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT:

Kelly Sheckler, Air Regulatory Management Section, Air Planning and Implementation Branch, Air and Radiation Division, U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960. The telephone number is [phone]. Ms. Sheckler can also be reached via electronic mail at [e-mail].

SUPPLEMENTARY INFORMATION:

I. Background

On July 18, 1997 (62 FR 38856), EPA promulgated a revised 8-hour ozone standard of 0.08 parts per million (ppm). In December 2002, Hamilton and Meigs counties in Tennessee and Catoosa county in Georgia (also known as the Chattanooga Ozone Area) entered into EPA's Early Action Compact (EAC) program.^[1] See 70 FR 50199 (August 26, 2005). As part of the EAC as a control strategy to meet the 1997 8-hour ozone national ambient air quality standard (NAAQS or standard), Tennessee added Hamilton County to the State's I/M rules at Chapter 29 of the Tennessee Air Pollution Control Regulations (TAPCR 1200-03-29) to require all light-duty motor vehicles registered in Hamilton County to be inspected annually for compliance with emissions performance and anti-tampering test criteria.² See id. The I/M program in Hamilton County began in April 2005. The Chattanooga Ozone Area met the EAC requirements by December 31, 2007, demonstrating attainment of the 1997 8-hour ozone NAAQS. As a result of meeting the EAC agreement, on April 2, 2008, EPA designated the Chattanooga Ozone Area as attainment for the 1997 8-hour ozone NAAQS. See 73 FR 17897. The ozone NAAQS was revised in 2008 to a value of 0.075 ppm and again in 2015 to 0.070 ppm. See 73 FR 16483 (March 27, 2008) and 80 FR 65292 (October 26, 2015). Hamilton County was designated as unclassifiable/attainment and attainment/unclassifiable for the 2008 and 2015 ozone NAAQS, respectively. See 40 CFR 81.343. Hamilton County is currently in attainment with all ozone NAAQS. See id.

On July 18, 1997, EPA set the 24-hour fine particulate matter (PM_2.5) NAAQS at 65 micrograms per cubic meter (µg/m³) and the annual PM_2.5 NAAQS at 15 µg/m³. See 62 FR 38652 (July 18, 1997). On January 5, 2005, EPA designated Hamilton County in Tennessee, Catoosa and Walker counties in Georgia, and a portion of Jackson County in Alabama (also known as the Chattanooga PM_2.5 Area) as nonattainment for the 1997 annual PM_2.5 NAAQS. See 70 FR 944 (January 5, 2005). On October 15, 2009, Tennessee submitted a PM_2.5 attainment SIP and identified the I/M program, which had already been implemented to comply with the ozone NAAQS, as a control measure for the on-road mobile sector. See 80 FR 56418 (September 18, 2015) and 80 FR 68253 (November 4, 2015). It was determined that no additional emission reductions were necessary for on-road mobile sources beyond the fully implemented (existing) I/M program because the Chattanooga PM_2.5 Area was modeled to attain the NAAQS with the current regulatory scheme in 2009. See id. On November 4, 2015, Hamilton County was redesignated to attainment for the 1997 annual PM_2.5 NAAQS. See 80 FR 68253. On August 24, 2016, EPA took final action to revoke the 1997 PM_2.5 NAAQS for areas designated attainment or in maintenance for the standard. See 81 FR 58010.

On May 15, 2018, a Tennessee law which states that “no inspection and maintenance program shall be employed in this state on or after the effective date of this act” was signed. See Tenn. Code Ann. § 68-201-119. The Tennessee law states that it “shall take effect [120] calendar days following the date on which the [EPA] approves a revised state implementation plan. . . .” See Motor Vehicles—Inspection and Inspectors—Air Pollution, 2018 Tennessee Laws Pub. Ch. 953 (H.B. 1782). Accordingly, Tennessee submitted the February 26, 2020, SIP revision requesting that EPA remove the requirements to implement an I/M program for Hamilton County. A description of the SIP revision and EPA's analysis is provided in Section II below.

II. What is EPA's analysis of Tennessee's submittal?

Through a letter dated February 26, 2020,^[3] Tennessee requested that TAPCR 1200-03-29 be removed from the Tennessee SIP. In addition, Tennessee requested that EPA remove the requirement for Hamilton County to implement an I/M program as part of the EAC that was approved by EPA into the non-regulatory portion of the Tennessee SIP on August 26, 2005. See 70 FR 50199. Tennessee also provided a noninterference demonstration to support the removal of the requirements for the I/M program in Hamilton County.

As discussed in Section I above, Hamilton County implemented the I/M program requirements as a control strategy in the EAC to meet the 1997 8-hour ozone NAAQS. Currently, Hamilton County is designated attainment, unclassifiable/attainment, or attainment/unclassifiable for all ozone and PM_2.5 NAAQS. See 40 CFR 81.343.

EPA is proposing to approve the removal of the I/M requirements for Hamilton County from the Tennessee SIP, including Chapter 29 of the Tennessee Air Pollution Control Regulations (TAPCR 1200-03-29).^[4] EPA is also proposing to find that the removal of the I/M program requirements for Hamilton County is consistent with CAA section 110(l). Section 110(l) of the CAA requires that a revision to the SIP not interfere with any applicable requirements concerning attainment, reasonable further progress (as defined in section 171), or any other applicable requirements of the CAA. EPA evaluates section 110(l) non-interference demonstrations on a case-by-case basis considering the circumstances of each SIP revision. EPA interprets section 110(l) as applying to all NAAQS that are in effect. For I/M SIP revisions, the most relevant pollutants to consider are ozone precursors (i.e., nitrogen oxides (NO_X) and volatile organic compounds (VOCs)).

As mentioned above, Tennessee's February 26, 2020, SIP revision included a non-interference demonstration to support the State's request to remove the SIP-approved I/M program requirements for Hamilton County. Tennessee's non-interference demonstration evaluates the impact that the removal of the I/M program for Hamilton County would have on the ability to attain and maintain any of the NAAQS. Based on the analysis below, EPA is proposing to find that removal of the I/M program requirements for Hamilton County meets the requirements of CAA section 110(l) because it would not interfere with attainment or maintenance of any NAAQS or any other requirement of the CAA.^[5 6 7]

Non-Interference Analysis for the Ozone NAAQS

As discussed in Section I above, on July 18, 1997 (62 FR 38856), EPA promulgated a revised 8-hour ozone standard of 0.08 ppm. Subsequently, on March 12, 2008, EPA revised both the primary and secondary NAAQS for ozone to a level of 0.075 ppm to provide increased protection of public health and the environment. See 73 FR 16436 (March 27, 2008). The 2008 ozone NAAQS retain the same general form and averaging time as the 0.08 ppm NAAQS set in 1997 but are set at a more protective level. Under EPA's regulations at 40 CFR part 50, the 2008 8-hour ozone NAAQS are attained when the 3-year average of the annual fourth highest daily maximum 8-hour average ambient air quality ozone concentrations is less than or equal to 0.075 ppm. See 40 CFR 50.15. On October 26, 2015 (80 FR 65292), EPA published a final rule lowering the level of the 8-hour ozone NAAQS to 0.070 ppm or 70 parts per billion (ppb) and retaining the same form.

Hamilton County is currently designated as attainment, unclassifiable/attainment, or attainment/unclassifiable for all ozone NAAQS.^[8] See 40 CFR 81.343. Ambient air quality monitoring for ozone is being conducted at two locations in the Chattanooga, TN-GA metropolitan statistical area (MSA).^[9] In the SIP submittal, the State provides recent 8-hour ozone design values in ppb (see Table 1). The values in Table 1 below indicate attainment of the 2015 8-hour NAAQS of 70 ppb.

Table 1—Hamilton County Monitor Design Values

Site name	Ozone design value, ppb
	2013-2015	2014-2016	2015-2017	2016-2018	2017-2019
Eastside Utility	66	68	67	66	64
Soddy Daisy	64	65	65	64	64

Tennessee's noninterference analysis includes modeling to calculate ozone precursor emissions, as well as a sensitivity analysis to demonstrate the impact of emissions increases on monitored ozone values. Tennessee's non-interference demonstration utilized EPA's MOVES2014 emission modeling system to estimate ozone precursor emissions for mobile sources, both on-road and non-road. Tennessee chose 2022 as the future year for the State's non-interference demonstration because it is the year that Hamilton County anticipates that it will cease implementation of the I/M program due to the CAA's SIP processing timeframe and the language of Tenn. Code Ann. § 68-201-119. The point source emissions for Hamilton County were obtained from the 2014 version 2 National Emissions Inventory (NEI) and grown to the year 2022 using the appropriate EPA growth factors or using engineering judgment based on potential growth in demand. For non-point sources, the inventory was developed using EPA established methodologies published by EPA,^[10] as detailed in Appendix G of the February 26, 2020, SIP revision. Tennessee calculated projected emissions in the year 2022 by adding all four sectors (on-road, point, non-road, and non-point) together.

Table 2 shows the total projected emissions in 2022 with the I/M program in Hamilton County. Table 3 shows the total projected emissions in 2022 without the I/M program in Hamilton County.^[11] By 2022, the emissions benefits resulting from Tennessee's I/M program for Hamilton County are predicted to be a 99.7 tons per year (tpy) reduction of NO_X and a 146.23 tpy reduction of VOCs. See Table 4. On a percentage basis, removal of the I/M program in Hamilton County is expected to result in a 1.1 percent increase in total NO_X emissions and a 1.5 percent increase in on-road VOCs.

Table 2—Hamilton County Area

[Total 2022 projected emissions of NO_X and VOC (in tpy) with the I/M program]

Sector	NOX	VOC
On-road	4,613	2,127
Point	1,314	825
Non-road	2,220	935
Non-Point	1,220	5,744
Total	9,367	9,632

Table 3—Hamilton County Area

[Total 2022 projected emissions of NO_X and VOC (in tpy) without the I/M program]

Sector	NOX	VOC
On-road	4,712	2,273
Point	1,314	825
Non-road	2,220	935
Non-Point	1,220	5,744
Total	9,467	9,778

Table 4—Summary of NO_X and VOC Emissions Increases Associated With Removing the Hamilton County From the I/M Program

	NOX Emissions in 2022	VOC Emissions in 2022
Total On-Road Emissions for Hamilton County in Current I/M Program (tpy)	4,613	2,127
Total On-Road Emissions after Removing Hamilton County from I/M Program (tpy)	4,712	2,273
Total Emissions for Hamilton County in Current I/M Program (all sectors) (tpy)	9,367	9,632
Total Emissions after Removing Hamilton County from I/M Program (all sectors) (tpy)	9,467	9,778
Emissions Increases (tpy)	99.7	146.2
Emissions Increases (% of On-Road Emissions for Hamilton County)	2.2%	6.9%
Emissions Increases (% of Total Emissions for Hamilton County, all sectors)	1.1%	1.5%

To further quantify the potential impact of removal of the I/M program, Tennessee completed a photochemical modeling sensitivity analysis. As shown in Table 5, the sensitivity analysis indicates that the largest increase in ozone concentration would be at the Eastside Utility monitor at 0.209 ppb.

Table 5—Results of Sensitivity Analysis, Predicted Increases of Ozone Concentrations at Monitors in the Chattanooga Ozone Area

Site name	2016-2018 ozone design value (ppb)	Predicted ozone increase due to combined NOX and VOC increases
Eastside Utility	66	0.209
Soddy Daisy	64	0.148

EPA has evaluated the State's analysis and preliminarily agrees with its findings and conclusions. EPA therefore proposes to find that removal of the SIP-approved I/M program requirements for Hamilton County would not interfere with any applicable requirement concerning attainment or maintenance of the ozone NAAQS.

Non-Interference Analysis for the PM _2.5 NAAQS

On July 16, 1997, EPA established an annual PM_2.5 NAAQS of 15.0 μg/m³, based on a 3-year average of annual mean PM_2.5 concentrations, and a 24-hour PM_2.5 NAAQS of 65 μg/m³, based on a 3-year average of the 98th percentile of 24-hour concentrations. See 62 FR 38652 (July 18, 1997). On August 24, 2016, EPA took final action to revoke the 1997 PM_2.5 NAAQS for areas designated attainment or in maintenance. See 81 FR 58010.

On September 21, 2006, EPA retained the 1997 annual PM_2.5 NAAQS of 15.0 μg/m³ but revised the 24-hour PM_2.5 NAAQS to 35 μg/m³, based again on a 3-year average of the 98th percentile of 24-hour concentrations. See 71 FR 61144 (October 17, 2006). On December 14, 2012, EPA retained the 2006 24-hour PM_2.5 NAAQS of 35 μg/m³ but revised the annual primary PM_2.5 NAAQS to 12.0 μg/m³, based again on a 3-year average of annual mean PM_2.5 concentrations. See 78 FR 3086 (January 15, 2013).

As discussed in Section I above, EPA published designations for the 1997 annual PM_2.5 NAAQS on January 5, 2005 (70 FR 944), and April 14, 2005 (70 FR 19844). On January 5, 2005, EPA designated the Chattanooga PM_2.5 Area nonattainment for the 1997 annual PM_2.5 NAAQS. See 70 FR 944. On November 4, 2015, Hamilton County was redesignated to attainment for the 1997 annual PM_2.5 NAAQS, and EPA approved a maintenance plan and reasonably available control measure demonstration for the Chattanooga PM_2.5 Area. See 80 FR 68253. The Chattanooga PM_2.5 Area has continued to attain the 1997 annual PM_2.5 NAAQS. On November 13, 2009, and on January 15, 2015, EPA published notices determining that the Hamilton County was designated unclassifiable/attainment for the 2006 24-hour PM_2.5 NAAQS and the 2012 annual PM_2.5 NAAQS, respectively. See 74 FR 58688 and 80 FR 2206, respectively.

In Tennessee's February 26, 2020, SIP revision, the State concluded that the removal of Hamilton County from Tennessee's SIP-approved I/M program would not interfere with attainment or maintenance of the PM_2.5 NAAQS for the reasons outlined below. First, photochemical modeling using source apportionment analysis, performed in connection with the November 13, 2014, redesignation request and associated maintenance plan for the Chattanooga PM_2.5 Area (also known as the Chattanooga PM_2.5 Redesignation Request and Maintenance Plan) showed that the greatest contribution to ambient PM_2.5 concentrations in the Chattanooga PM_2.5 Area is from secondary sulfates, which are formed from atmospheric reactions with sulfur dioxide (SO₂), and that a very small portion of the total PM_2.5 in the atmosphere is formed from NO_X and VOCs.^[12] Second, when the 2022 projected NO_X emissions in the I/M removal request are compared to the emissions inventory for 2022 within the Chattanooga PM_2.5 Redesignation Request and Maintenance Plan, the projections in the I/M removal request are 2,850 tons less. Third, the Chattanooga PM_2.5 Redesignation Request and Maintenance Plan did not rely on the I/M program as a permanent and federally-enforceable measure to maintain compliance with the PM_2.5 NAAQS, and the approved maintenance plan demonstrates maintenance through 2025 without the I/M program (i.e., projected on-road mobile emissions were modeled without the I/M program). Furthermore, the pollution control systems for light-duty gasoline vehicles subject to the I/M program are not designed to reduce emissions of direct PM_2.5 and sulfate (i.e., the primary precursor for PM_2.5 formation in the Southeast); therefore, removing counties from the program will not have any impact on ambient concentrations of PM_2.5 NAAQS.

In addition, Tennessee provided information regarding the monitored values of PM_2.5 in the Chattanooga PM_2.5 Area. Ambient air monitoring shows that the 2019 design value for the 24-hour PM_2.5 NAAQS for the Chattanooga PM_2.5 Area is 19 µg/m^[3] , which is below the 24-hour NAAQS of 35 µg/m^[3] . The 2019 design value for the 2012 annual PM_2.5 NAAQS for the Chattanooga PM_2.5 Area is 8.8 µg/m^[3] , which is below the 2012 annual NAAQS of 12.0 µg/m^[3] .^[13] The small increases in NO_X emissions of 1.1 percent and VOC emissions of 1.5 percent that are anticipated to result in 2022 from the removal of the I/M program in Hamilton County is expected to only cause a small increase (if any) in the PM_2.5 design value for the Chattanooga PM_2.5 Area.

EPA has evaluated the State's analysis and preliminarily agrees with its findings and conclusions. Therefore, EPA proposes to find that removal of the SIP-approved I/M program requirements for Hamilton County would not interfere with continued attainment or maintenance of the PM_2.5 NAAQS.

Non-Interference Analysis for the 2010 Nitrogen Dioxide (NO ₂) NAAQS ^[14]

The 2010 1-hour NO₂ standard is set at 100 ppb, based on the 3-year average of the 98th percentile of the yearly distribution of 1-hour daily maximum concentrations. See 75 FR 6474 (February 9, 2010). On February 17, 2012, EPA designated all counties in Tennessee as unclassifiable/attainment for the 2010 NO₂ NAAQS. See 77 FR 9532.

Based on the technical analysis in Tennessee's February 26, 2020, SIP revision, the projected increase in total NO_X emissions (of which NO₂ is a component) in 2022 associated with the removal of Hamilton County from the I/M program is 1.1 percent. All NO₂ monitors in the State are measuring below the annual NO₂ standard, and all near road monitors are measuring well below the 1-hour NO₂ standard. There are no NO₂ monitors in the Chattanooga PM_2.5 Area.

EPA has evaluated the State's analysis and preliminarily agrees with its findings and conclusions. Therefore, EPA proposes to find that removal of the SIP-approved I/M program requirements for Hamilton County would not interfere with continued attainment or maintenance of the NO₂ NAAQS.

Non-Interference Analysis for the Carbon Monoxide (CO) NAAQS

EPA promulgated the CO NAAQS in 1971 and has retained the standards since its last review of the standards in 2011. The primary NAAQS for CO consist of: (1) An 8-hour standard of 9 ppm, not to be exceeded more than once in a year (i.e., the second highest, non-overlapping 8-hour average concentration cannot exceed the standard); and (2) a 1-hour average of 35 ppm, not to be exceeded more than once in a year. Hamilton County has always been designated as unclassifiable/attainment for the CO NAAQS.

In Tennessee's February 26, 2020, SIP revision, the State concluded that the removal of Hamilton County from the SIP-approved I/M program would not interfere with attainment or maintenance of the CO NAAQS. MOVES2014 mobile emissions modeling results show an increase in CO emissions of 6.9 percent in Hamilton County in 2022 as a result of removing the I/M program for Hamilton County. This increase is not expected to interfere with continued attainment of the CO NAAQS in Hamilton County. Design values for Tennessee for the 1-hour and 8-hour CO NAAQS in 2019 were 1.6 and 1.8, respectively, which are less than 20 percent of the CO NAAQS for both the 1-hour and 8-hour standards.

EPA has evaluated the State's analysis and preliminarily agrees with its findings and conclusions. For these reasons, EPA proposes to find that removal of the SIP-approved I/M program requirements for Hamilton County would not interfere with continued attainment or maintenance of the CO NAAQS.

III. Proposed Action

EPA is proposing to approve the removal of the I/M requirements for Hamilton County from the Tennessee SIP. EPA is proposing to approve the removal of the I/M program requirements for Hamilton County from the federally approved SIP because removing the requirements is consistent with the CAA and applicable regulations.

IV. Statutory and Executive Order Reviews

Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the Act and applicable Federal regulations. See 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, provided they meet the criteria of the CAA. This proposed action merely proposes to approve state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this proposed action:

• Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Orders 12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
• Is not an Executive Order 13771 (82 FR 9339, February 2, 2017) regulatory action because SIP approvals are exempted under Executive Order 12866;
• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not an economically significant regulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001);
• Is not subject to requirements of Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA; and
• Does not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).

The SIP is not approved to apply on any Indian reservation land or in any other area where EPA or an Indian tribe has demonstrated that a tribe has jurisdiction. In those areas of Indian country, the rule does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), nor will it impose substantial direct costs on tribal governments or preempt tribal law.

List of Subjects in 40 CFR Part 52

• Environmental protection
• Air pollution control
• Carbon monoxide
• Incorporation by reference
• Intergovernmental relations
• Lead
• Nitrogen dioxide
• Ozone
• Particulate matter
• Reporting and recordkeeping requirements
• Sulfur oxides
• Volatile organic compounds

Authority: 42 U.S.C. 7401 et seq.

Dated: May 29, 2020.

Mary Walker,

Regional Administrator, Region 4.

Footnotes

1.  In December 2002, several states submitted early action compact agreements pledging to meet the 1997 8-hour ozone standard earlier than required. The states had to meet certain criteria and milestones. The most significant milestone was that the EAC areas had to attain the 1997 8-hour ozone standard by December 31, 2007.

2.  The I/M program in Hamilton County was not required by the CAA because the Act only requires I/M programs in ozone nonattainment areas classified as moderate, serious, severe, or extreme.

3.  EPA received Tennessee's SIP revision on February 27, 2020.

4.  EPA cannot propose to remove TAPCR 1200-03-29 from the SIP in its entirety at this time because this regulation also applies to Rutherford, Sumner, Williamson, and Wilson Counties. Therefore, EPA is proposing to remove Hamilton County from TAPCR 1200-03-29.

5.  The initial designations for the PM₁₀ NAAQS were completed on March 15, 1991. See 56 FR 11101. The entire state of Tennessee was designated as attainment for PM₁₀ and has been attainment for every PM₁₀ standard thereafter. The pollution control systems for light-duty gasoline vehicles subject to the I/M program are not designed to reduce emissions of PM₁₀; therefore, removing the I/M program requirements will not have any impact on ambient concentrations of PM₁₀. EPA proposes to find that removal of the SIP-approved I/M program requirements for Hamilton County would not interfere with continued attainment or maintenance of the PM₁₀ NAAQS.

6.  On June 22, 2010, EPA revised the 1-hour SO₂ NAAQS to 75 ppb which became effective on August 23, 2010. See 75 FR 35520. On January 9, 2018, EPA designated most of the state of Tennessee, including Hamilton County, as attainment/unclassifiable for the 2010 SO₂ NAAQS. See 83 FR 1098. EPA has designated Sullivan County, Tennessee nonattainment and Sumner County as unclassifiable for the 2010 1-hour SO₂ NAAQS. See 78 FR 47191 (August 5, 2013), and 81 FR 45039 (July 12, 2016). The pollution control systems for light-duty gasoline vehicles subject to the I/M program are not designed to reduce emissions for SO₂; therefore, removing the I/M program requirements will not have any impact on ambient concentrations of SO₂. EPA proposes to find that removal of the SIP-approved I/M program requirements for Hamilton County would not interfere with continued attainment or maintenance of the SO₂ NAAQS.

7.  On November 12, 2008, EPA promulgated a revised lead NAAQS of 0.15 µg/m3. . See 73 FR 66964. On November 22, 2011, EPA designated a majority of the State of Tennessee, including Hamilton County as unclassifiable/attainment for the 2008 lead NAAQS. The Bristol Area in Sullivan County was designated as nonattainment; and the Knox County Area was later designated as unclassifiable. See 76 FR 72907; see also 75 FR 71033 (November 22, 2011). Subsequently, the Bristol Area was redesignated to attainment. See 81 FR 44210 (July 7, 2016). Effective January 1, 1996, EPA banned the sale of leaded fuel for use in on-road vehicles. The pollution control systems for light-duty gasoline vehicles subject to the I/M program are not designed to reduce emissions for lead; therefore, removal of the I/M program requirements would not cause an increase in emissions of lead. EPA proposes to find that removal of the SIP-approved I/M program requirements for Hamilton County would not interfere with continued attainment or maintenance of the lead NAAQS.

8.  Visit https://gispub.epa.gov/​air/​trendsreport/​2019/​#home or https://www.epa.gov/​outdoor-air-quality-data for air quality data including current status and trends for all NAAQS.

9.  The Chattanooga TN-GA MSA is comprised of Hamilton, Marion, and Sequatchie counties in Tennessee and Catoosa, Dade, and Walker counties in Georgia.

10.  See 2017 NEI Final Plan: Revised July 2018, available at https://www.epa.gov/​sites/​production/​files/​2018-07/​documents/​2017_​nei_​plan_​final_​revised_​jul2018.pdf.

11.  Since the I/M program only impacts emissions in the on-road sector, the projected emissions in other sectors (point, non-road and non-point) are the same between the “with the I/M program” and the “without the I/M program” scenarios.

12.  See document EPA-R04-OAR-2014-0904-0002 at regulations.gov.

13.  The design value for the Chattanooga PM_2.5 Area is at monitor 132950002 in Walker County, Georgia.

14.  The annual standard of 53 ppb is based on the annual mean concentration. See 36 FR 8186 (April 30, 1971).