Rice University logo
Top blue bar image Cohan Research GroupCohan Research Group

Contact Us

Dr. Daniel Cohan
Associate Professor
Civil and Environmental Engineering
Rice University
6100 Main Street MS 519
Houston, TX 77005

Phone: 713-348-5129
Office: Keck Hall 116B
Email: cohan 'at' rice.edu

Retrospective Assessments of Air Quality Plans 

While EPA sets and revises National Ambient Air Quality Standards (NAAQS) for a criteria air pollutant, it is the States that must develop state implementation plans (SIPs) for attaining those standards. Despite the critical importance of these plans to air quality, the efficacy of SIPs has rarely been examined retrospectively. Retrospective analysis of progress made can be highly valuable in planning for renewed efforts at attainment as NAAQS limits are tightened.

Our research group conducted the most systematic analyses of SIPs developed to meet the 84 ppb 8-hr ozone standards (Pegues et al, 2012) and the 15 μg/m3 fine particulate matter standards (Cohan and Chen, 2014). In both cases, the NAAQS were achieved on-time in the vast majority of regions, and models were accurate to slightly conservative in predicting air quality improvements. Regions required to prepare attainment plans achieved slightly faster improvements in air quality beyond the overall trend nationwide. However, most SIPs did little to integrate across the ozone and particulate matter planning, and did not quantify the costs or health benefits of their emissions reductions measures.

Funding: National Science Foundation CAREER Award and NASA Air Quality Applied Sciences Team

Participants: Andrew Pegues, Ran Chen, Wei Zhou 

Associated articles: Pegues et al 2012; Cohan and Chen 2014; Zhou et al 2013; Zhou et al 2014