Reductions in Ground-Level Ozone Pollution through Urban Heat Island Mitigation Strategies Including Rehabbing Land Occupied for Transportation Related Uses: Case Study of Fresno, CA

摘要

The urban heat island effect is the phenomenon where developed areas tend to be warmerthan their surrounding countryside. Excessively warm conditions can worsen ground-levelozone air pollution problems as ozone concentrations are dependent on levels ofphotochemical reactivity affected by temperature. Among the causes of heat islands are thethermal properties of materials used in urban areas, including those used for transportation,such as pavement. Heat island mitigation strategies, including cool pavement technologies andshading of pavement, among others, represent opportunities to tackle ground-level ozonepollution problems through temperature.Two mitigation scenarios for the Fresno, California region, an area heavily impacted by poorozone conditions, indicate that heat island mitigation strategies can bring modest ozonebenefits. Conservative estimates modeled using the Mitigation Impact Screening Tool showsthat the two mitigation scenarios could reduce temperature by 0.8oF to 5.7oF and yield 3 to 12percent reductions in the typical excess of ozone in Fresno over California state ambient airquality standards. Cool roofs provide relatively more benefit in the two scenarios, as doesincrease vegetation, including vegetation that shades land occupied for transportation uses.Cool pavements provide some benefit, with greater future benefit possible with furtherdevelopments in technology.