Developing an evidence based zoning ordinance to reduce exposure to traffic-related ultrafine particles

Abstract

Introduction: As a result of increasing evidence that traffic-related ultrafine particles (UFP) present a health risk there is a need to develop protective measures. In the absence of regulations, community-level responses are particularly important. Methods: We drew on the broader literature as well as findings from our own research to develop a zoning ordinance for the City of Somerville, MA, USA. Previous work included near-highway land use regression (LUR) modeling, individualized exposure assessment and demonstration of associations with blood biomarkers of inflammation for residents of Somerville. Additionally, we conducted indoor and outdoor monitoring for near highway housing to test efficacy of current HVAC filtration at reducing UFP levels. Results: Our proposed rule would apply to new residential developments and significantly rehabilitated housing near major roadways. Based on the LUR models, housing would be included if it was <100 feet (30 m) from roads with >10,000 vehicle trips/day (v/d). The buffer distance would increase an additional 100 feet for every 10,000 additional v/d to a maximum buffer of 500 feet (150 m) for roadways of >50,000 v/d. UFP levels within housing inside the buffer would be required to be 80% lower than outdoor levels based on predicted health risk and feasibility. There would also be credits for use of physical barriers, distance buffers and protective placement of air intake vents. A detailed air monitoring protocol was developed to measure compliance. Our ordinance is currently under consideration for inclusion in the zoning code for the city. Conclusions: Our ordinance, which was developed cooperatively with the city government, shows the viability of local regulations that protect against exposure to traffic-related UFP. There is a need for research to test whether measures of this sort effectively reduce exposure and are also associated with health benefits.