Motor vehicles emit diverse air pollutants, and adverse health outcomes associated with vehicle air pollutants include cancer, respiratory disease, and pre-mature mortality. Vehicle air pollutant concentrations and associated adverse health outcomes are significantly higher among people living near freeways and busy roadways. Now, San Francisco is poised to become the first city in the country to take such action to protect residential development from the harmful effects of air pollution from traffic.
Health research has consistently demonstrated that children living within 100-200 meters of freeways or busy roadways have poorer lung function and more asthma and respiratory symptoms than those living further away. In 2005, the California Air Resources Board issued guidance on preventing roadway related air quality conflicts, recommending localities avoid placing new sensitive uses within 500 ft of many freeways. In 2007, the City’s environmental review of the Eastern Neighborhoods Zoning and Area Plans identified roadway air pollution exposure on sensitive uses as a significant environmental impact. The Environmental Impact Statement for these plans required project level assessment and appropriate ventilation system to mitigate air quality impacts on sensitive uses. Subsequently, the San Francisco Department of Public Health (SFDPH) developed guidance to assess and prevent health impacts associated with locating new residential uses near roadway air pollution hot spots. Since 2008, the San Francisco Planning Department have been requiring developers of sensitive use near busy roadways to conduct air quality site assessment under the guidance of SFDPH.
In November 2008, the San Francisco Board of Supervisors adopted a new law imposing regulations to prevent health impacts from air pollution hotspots created by busy roadways. The regulation requires that developers screen sensitive use projects for proximity to traffic and calculate the concentration of PM 2.5 from traffic sources where traffic volumes suggest a potential hazard. If modeled levels of traffic-attributable PM 2.5 at a project site exceed an action level (currently set at 0.2 ug/m3) developers would be required to incorporate ventilation systems to remove 80% of PM2.5 from outdoor air. The regulation would not place any requirements on proposed sensitive uses if modeled air pollutant levels fall below the action threshold.
