Cool Roofing Materials Worsen Air Pollution

In a groundbreaking study released on Monday, scientists at the South Coast Air Quality Management District and the University of Southern California have found that widespread installation of certain "cool roof" materials in the region could slightly increase ozone and fine particulate pollution levels.

The study explains how the predicted increase in ozone levels can be minimized or avoided by requiring more comprehensive performance standards for cool-roofing materials. However, small increases in fine particulate (PM2.5) levels are predicted to occur with or without enhanced standards, Science Daily reported.

"Cool roofs have many benefits, including reduced energy use for cooling and mitigation of the significant health impacts of heat waves." Wayne Nastri, the university's executive officer, said.

"While the future, widespread use of certain kinds of cool roofing materials could slightly increase air pollution levels, we in no way want to discourage this technology. This study shows what needs to be done to help cool our cities and avoid increasing ozone levels as an unintended consequence."

The study, titled "Air Quality Implications of Widespread Adoption of Cool Roofs on Ozone and Particulate Matter in Southern California," was published in the Proceedings of the National Academy of Sciences. They used sophisticated meteorology and air quality computer models, measurements of cool roofing materials and detailed databases of the region's rooftops to predict the air quality impacts of the increasing use of cool roof materials—typically light-colored and highly reflective—that are expected to result from current statewide energy efficiency standards.