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Federal Register / Vol. 86, No. 156 / Tuesday, August 17, 2021 / Rules and Regulations government from maintaining an I/M
program at the state or local level.
The one exception where Tennessees air quality does not meet the NAAQS is a portion of Sullivan County, Tennessee, that encompasses the Eastman Chemical Plant. In 2013, EPA
designated a portion of Sullivan County nonattainment for the 2010 1-hour SO2
NAAQS. CAA section 191 requires Tennessee to develop a plan to bring the area back in attainment with the SO2
NAAQS as expeditiously as possible. As noted in the June 2020 NPRMs 85 FR
35037 and 85 FR 35607 and the April SNPRM 86 FR 21248, 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.
Comment A6: Some commenters assert that removal of Tennessees I/M
program would cause greater increases or would exacerbate issues with pollutants uninvolved in ozone formation i.e., pollutants other than NOX or VOC. Others worry that removing the I/M program as Tennessee grows warmer would result in increased ozone formation. The commenters also mention concerns about greater emissions in PM pollution, CO, and greenhouse gases GHGs i.e., methane and carbon dioxide CO2. Some of the commenters that are worried about an increase in GHGs have concerns stemming from a general worry about climate change. Another commenter expresses concerns about increases in emissions in general, but also acknowledges that ozone formation in Tennessee appears to be limited by NOX.
Response A6: With regard to PM
emissions, EPA noted in the June 2020
NPRMs and the April 2021 SNPRM that I/M programs are not designed to reduce direct PM emissions. In fact, EPAs state-of-the-science Motor Vehicle Emission Simulator modeling system, MOVES, calculates no benefit for direct PM emission reductions from an I/M
program. In addition, EPA notes that, separate and apart from I/M, there may be PM emission benefits in future years due to expected fleet turnover and continued implementation of EPAs engine and fuel standards. Furthermore, PM formation in Tennessee is dominated by sulfates. As noted in the June 2020 NPRMs and the April 2021
SNPRM, Hamilton County and the Middle Tennessee Area are well in compliance with the PM standards.
As noted in the June 2020 NPRMs and the April 2021 SNPRM, Hamilton
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County and the Middle Tennessee Area are well in compliance with the CO
standards. In support of its noninterference demonstration and as discussed in EPAs June 2020 NPRMs and April SNPRM, Tennessee used the MOVES2014b mobile emissions modeling to determine the change in emissions for CO resulting from the removal the I/M program in Hamilton County and the Middle Tennessee Area.
The results show an increase in CO
emissions of 6.9 percent for Hamilton County, and of 6.1 percent for the Middle Tennessee Area for scenarios in 2022 with and without the I/M program.
However, there is a decrease in total CO
emissions from all source categories from 2014 to 2022. For reasons described in the April 2021 SNPRM, EPA has concluded the removal of the I/M program from Hamilton County and the Middle Tennessee Area is consistent with the CAA.
In terms of ozone, EPA agrees with the commenter that Tennessee is NOX
limited, making it the precursor of most consideration related to potential impacts. As discussed in the April 2021
SNPRM, there is a decrease in total NOX
emissions from all source categories from 2014 to 2022. EPA also notes that the I/M program does not have a direct impact on GHGs and is not designed to reduce emissions associated with climate change, such as GHGs.
Comment A7: Some commenters assert that rural and urban areas face different issues when it comes to pollution and air quality. In particular, commenters are concerned that dropping the I/M program in urban areas, which they claimed tend to have significantly more emissions, would increase emissions not only for those areas, but also for surrounding rural areas, and potentially cause future violations of the standard.
Response A7: EPA agrees that air quality is important. As discussed in EPAs June 2020 NPRMs and April 2021
SNPRM, Hamilton County and the Middle Tennessee Area are in attainment or maintenance for all criteria pollutants. The Agency has provided detailed information showing that the monitors in Hamilton County and the Middle Tennessee Area that collect complete, quality assured and certified data for recent years have design values that are less than the ozone, PM, and CO standards. The design values and recently certified data, in combination with the emissions inventory analysis, demonstrate that the areas will continue to meet the NAAQS, even as population and vehicles increase not only in Hamilton County and the Middle Tennessee Area, but
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statewide. While commenters seem to make a distinction between emissions from urban areas versus rural areas, the commenters do not provide information to indicate that removal of the I/M
program in Hamilton County and the Middle Tennessee Area will cause a violation of the NAAQS in those areas or any surrounding rural areas. As mentioned in Response A4, EPA also notes that removal of the I/M program from the Tennessee SIP does not impact Federal vehicle and fuel standards that EPA has promulgated in separate rulemakings, and such standards will continue to result in significant emission reductions from the operation of vehicles, whether in rural or urban areas.
Comment A8: A commenter implies that removal of the I/M program will interfere with future visibility at the Great Smoky Mountains National Park.
Response A8: EPA disagrees with the commenters assertion that removal of the I/M program will interfere with visibility at the Great Smoky Mountains National Park. Visibility impairment in the Southeast is primarily dominated by sulfates. Sulfate particles form in the air from SO2 gas. Most of this gas is released from coal-burning power plants and other industrial sources, such as smelters, industrial boilers, and oil refineries. As discussed in the June 2020
NPRMs and the April 2021 SNPRM, the pollution control systems for light-duty gasoline vehicles subject to the I/M
program are not designed to reduce emissions of SO2 or the broader group of sulfates. In addition, as discussed in the April 2021 SNPRM, total NOX
emissions in 2022 without the I/M
program are significantly less than total NOX emissions in 2014 for the Middle Tennessee Area and Hamilton County.19
EPA also notes that there are separate CAA requirements related to visibility impairment, known as regional haze, that all states must comply with.
Removal of the I/M program will not remove these requirements which are separate and apart from the I/M
requirements that individual areas may have.
Comment A9: Several commenters express concerns about population and vehicle growth and the possible impacts on air quality.
Response A9: As mentioned in more detail in this final rulemaking, vehicles are, and continue to become, cleaner because of EPAs engine and fuel standards. Although the population may grow and lead to more vehicles, new vehicles will be covered by the most 19 NO emissions can convert to visibility X
impairing nitrates in the atmosphere.

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