EPA Research Partner Support Story: Meeting air quality and climate goals simultaneously
Partner: Connecticut Department of Energy and Environmental Protection (CT DEEP)
Challenge: Meeting air quality and climate goals simultaneously
Resource: Simulating air pollutant emissions and ozone impacts of state and regional greenhouse gas mitigation strategies
Project Period: 2021 – Present
The state of Connecticut is struggling to meet the 2008 and 2015 National Ambient Air Quality Standards (NAAQS) for ozone (O3)—largely due to the flow of ozone and precursor emissions from neighboring states. However, CT and many upwind states have committed to deep decarbonization goals, and to meet these targets, the states will have to greatly increase their adoption of energy efficiency, renewable electricity, and vehicle electrification. These measures also tend to reduce air pollutant emissions, and thus have the potential to help CT attain the O3 NAAQS.
“As a state that struggles to attain both the 2008 and 2015 health-based ozone standards, Connecticut truly appreciates EPA’s partnership and assistance in developing new tools capable of quantifying co-benefits and timing from national and state-level energy policies that will inform and assist in planning to reduce ozone precursor emissions in our state.” – CT DEEP Acting Chief of the Bureau of Air Management Paul Farrell
EPA ORD researchers, EPA Region 1 New England), and the Joint Global Change Research Institute (JGCRI) collaborated with CT DEEP to apply the GLIMPSE modeling framework to examine several mitigation scenarios. One of these scenarios, StateTargets, simulated the impact of state greenhouse gas (GHG) reduction targets and onroad vehicle electrification targets. The second, NetZeroZEV, imposed a national target to reduce net CO2 emissions to zero by 2050, combined with the national application of the onroad vehicle electrification targets. The mitigation scenarios both yielded NOx reductions. For example, in 2032, national NOx emissions under NetZeroZEV were reduced by 5.3%. By 2050, this had grown to 21%.
The project team also explored ways to translate these emission changes into insights about O3 attainment. Preliminary results suggest that the NOx reductions under these decarbonization scenarios could reduce O3 concentrations at CT monitoring sites by 7-11 ppb by 2032 relative to 2023, with reductions growing to nearly 15-20 ppb by 2050. This research provides CT DEEP with quantitative estimates of O3 co-benefits, showing that these benefits are expected to occur at a magnitude and timing that is relevant from an air quality planning context.
CT DEEP staff were beta testers and provided valuable feedback on the GLIMPSE software and Users’ Guide which were released in June 2023. The project team is continuing to work with CT DEEP to identify management strategies to achieve both air quality and climate benefits.