Under provisions of the Clean Air Act Amendment (CAAA), the U.S. Environmental Protection Agency (EPA) designated nine counties in the Cincinnati area as a nonattainment area for ozone under the 2015 ozone standard. Nonattainment means that the area is not meeting the national ambient air quality standard. Ozone is formed through photochemical reactions created when sunlight reacts with volatile organic compounds, or VOCs, and oxides of nitrogen (NOx). VOCs and NOx occur from incomplete combustion of fossil fuels.
How is Environment defined?
In April 2018, the U.S. Environmental Protection Agency (EPA) designated portions of nine counties in the Cincinnati area as a nonattainment area for ozone under the 2015 ozone standard. The 2015 Cincinnati ozone nonattainment area is Lawrenceburg Township in Dearborn County, Indiana; portions of the Kentucky counties of Boone, Campbell and Kenton; and the Ohio counties of Butler, Clermont, Clinton, Hamilton and Warren.
How is the OKI region doing?
Following progress in reducing fine particle pollution, the region has attained the annual PM2.5 standards. The area must continue to maintain the standards, keep previous regulatory commitments, and continue to demonstrate transportation conformity. PM2.5 refers to a complex mixture of fine particulates, primarily from fossil fuel combustion. It is emitted directly and will also form indirectly through reactions with precursor emissions, especially NOX. A primary contributor to transportation-related PM2.5 is diesel emissions.
The U.S. Environmental Protection Agency (EPA) requires the monitoring of six air pollutants due to their harmful effect on human health. These “criteria” pollutants are ozone, particulate matter (fine and course particulates), carbon monoxide, sulfur dioxide, nitrogen dioxide; and lead. Monitors have recorded high concentrations of ozone and particulates, which have frequently caused the OKI region to exceed health-based standards. The good news:Ozone concentrations in the region have dropped 21 percent and fine particulates (PM2.5) have decreased 39 percent since 2000. In comparison, ozone and PM2.5 concentrations in the U.S. have dropped 19 percent and 43 percent, respectively.
Ozone Concentration Levels 2000-2018
Fine Particulates (PM2.5) Concentration Levels ug/m3 2000-2019
Pollutant emissions from motor vehicles can be a major contributor to poor air quality. In the OKI region, these emissions account for about one-third of carbon dioxide (CO2) equivalent and fine particulate emissions. Motor vehicles account for up to half of emissions that, when combined with sunlight, form harmful ozone. The “ozone-precursor” emissions include volatile organic compounds (VOC) and oxides of nitrogen (NOx). The tables below show county-level motor vehicle emissions in tons per year (NOx and VOC) and million metric tons per year (CO2) through 2050, as estimated by OKI’s activity-based model.