Air Quality Impacts

Regional Air Quality Status

The National Ambient Air Quality Standards (NAAQS) are set by the U.S. EPA to protect public health and the environment. Of the five monitored air pollutants (carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone, and particulate matter) the entire OKI region is currently considered a “maintenance” area for ozone. The 2008 ozone area (Map 1) includes the counties of Butler, Clermont, Clinton, Hamilton, and Warren in Ohio; a portion of the counties of Boone, Campbell and Kenton in Kentucky; and a portion of Dearborn County Indiana. The region is also classified as a maintenance area for the 2015 NAAQS. The 2015 ozone area (Map 2) includes the counties of Butler, Clermont, Hamilton, and Warren in Ohio; and a portion of the counties of Boone, Campbell and Kenton in Kentucky.

On June 9, 2022, the U.S. Environmental Protection Agency (EPA) found that the Cincinnati, Ohio area had attained the 2015 ozone NAAQS and redesignated the Ohio portion of the area to attainment. This area includes the Ohio counties of Butler, Clermont, Hamilton, and Warren. EPA also approved Ohio’s motor vehicle emission budgets and maintenance plan. Counties in the Cincinnati area designated in the 2015 ozone NAAQS are shown in Map 2. On July 28, 2023, EPA found that the Kentucky portion of the Cincinnati area had attained 2015 ozone NAAQS and has been redesignated to a maintenance area. Nonattainment and maintenance areas must demonstrate transportation conformity.  Transportation conformity is a mechanism to ensure that federal funding and approval are given to those transportation activities that are consistent with air quality goals as contained in the State Implementation Plans (SIPs). OKI is responsible for the air quality conformity determination for the region’s Transportation Plan and Transportation Improvement Program. 

Transportation Conformity

All maintenance areas are subject to transportation conformity requirements. OKI is responsible for the air quality conformity determination for the region’s Metropolitan Transportation Plan and Transportation Improvement Program. 

This 2050 Metropolitan Transportation Plan Update and FY 24-27 TIP includes 102 recommended projects, which, due to their scope and regional significance, are subject to transportation conformity requirements (non-exempt projects). A new regional emissions analysis and finding of conformity is required. The results of the regional emissions analysis are shown in the tables below. The 2050 Plan E + C scenario was used to demonstrate the quantitative conformity finding.

OKI has determined through the quantitative analysis, the following findings:

  • The implementation of this OKI 2050 Metropolitan Transportation Plan Update will result in motor vehicle emissions that are consistent with the air quality goals of State Implementation Plans (SIPs).
  • The region’s ozone forming vehicle emissions do not exceed the established motor vehicle emissions budgets for 2020 through 2050.
  • OKI qualitatively finds that no goals, directives, recommendations or projects identified in the OKI 2050 Metropolitan Transportation Plan Update contradict, in a negative manner, any specific requirements or commitments of the applicable SIP.
  • The applicable implementation plan in Kentucky does not contain any transportation control measures (TCM’s), therefore; nothing in OKI 2050 Metropolitan Transportation Plan Update can interfere with their timely implementation.

    Impact of the 2050 Plan on Motor Vehicle Emissions

    The air quality impacts of the 2050 Plan have been forecasted using OKI’s Travel Demand Model and EPA’s Motor Vehicle Emissions Model (MOVES). Scenarios were developed for 2030, 2040 and 2050 to demonstrate air quality impacts in the region.

    • 2020– Existing transportation infrastructure, travel patterns, and OKI 2020 socio-economic characteristics.
    • 2030 EC – Existing transportation infrastructure, TIP FY 2024-2027 projects, and OKI 2030 socio-economic characteristics.
    • 2030 Vision – Existing transportation infrastructure, TIP FY 2024-2027 projects, OKI 2030 socio-economic characteristics, connected and autonomous vehicles (CAV) usage increases to 2.0%, vehicle occupancy increases by 5.0%.
    • 2040 Plan – Existing transportation infrastructure, TIP FY 2024-2027 projects, Plan projects through 2039, and OKI 2040 socio-economic characteristics.
    • 2040 Vision – Existing transportation infrastructure, TIP FY 2024-2027 projects, OKI 2040 socio-economic characteristics, connected and autonomous vehicles (CAV) usage increases to 12%, vehicle occupancy increases by 25%.
    • 2050 Plan – Existing transportation infrastructure, TIP FY 2024-2027 projects, all Plan projects, and OKI 2050 socio-economic characteristics.
    • 2050 Vision – Existing transportation infrastructure, TIP FY 2024-2027 projects, all Plan projects, OKI 2050 socio-economic characteristics, connected and autonomous vehicles (CAV) usage increases to 31%, vehicle occupancy increases by 40%.

     

    The Plan, through recommendations to increase transit availability, improve traffic operations and reduce roadway bottlenecks, will result in fewer vehicle emissions of ozone-forming volatile organic compounds (VOC) and oxides of nitrogen (NOx) and fewer emissions of greenhouse gases (expressed as carbon dioxide equivalent).

    Going beyond a conformity determination we find that if the Vision scenario was realized in 2050, emissions would have significant impacts as shown in the table. The 2050 Vision scenario reduces daily vehicle miles traveled (VMT) by more than two thirds of 2020 Base year levels, daily hours of delay by more than 100 percent of 2020 Base year levels, and percent of congested VMT by 6.8 percent of 2020 Base year levels. The reduction in daily VMT and hours of delay in the 2050 Vision scenario would result in a reduction of VOC and NOx by 65 percent and 86 percent, respectively, while reducing daily carbon dioxide emissions by 46 percent of 2020 Base year levels.

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