Which specific urban policies should be implemented by local authorities to achieve a health objective seeking reducing air pollution-attributable mortality?

BACKGROUND AND AIM: Public policies aiming at decreasing air pollutants such as fine particulate matter (PM2.5) are often designed without targeting an explicit health benefit and without carrying out cost-benefit analyses, therefore possibly limiting their adoption. We therefore developed a transdisciplinary backward and forward approach. METHODS: We first defined health objectives (corresponding to decreases by 33%, 50% and 67% in PM2.5-attributable mortality in 2030 compared to 2016), then identified which PM2.5 reductions and urban policies allowed to meet the health targets (backward approach), and finally conducted health impact and cost-benefit analyses of these policies (forward approach). The urban policies were related to wood heating and traffic, the two main emitting sectors in the considered area (Grenoble conurbation, France). The forward approach also considered the health and economic impacts related to changes in physical activity and carbon dioxide emissions. RESULTS:We showed that the most ambitious health target (-67%) could be achieved in 2030 by replacing all inefficient wood heating equipment by pellet stoves and by reducing by 36% the traffic of private motorized vehicles. Such a reduction in traffic requires to increase active modes share (walking, ...), which would also induce substantial increases in physical activity, and additional health benefits beyond the initial health target. Wood heating system replacement and the strategies maximizing active mobility, which are those that did not require massive investment in public transport, were the most cost-effective policies. Many benefits would be linked to the increase in physical activity: annual net benefits were between €468 and €615 per capita for policies with report on active modes, compared to between €151 and €258 for those without. CONCLUSIONS:Urban policies strongly reducing air pollution-attributable mortality can be identified by backward transdisciplinary approaches, and they can be cost-efficient. To our knowledge, such approach has not previously been carried out at the city or national level. KEYWORDS: Dispersion model, economic analysis, fine particulate matter (PM2.5), health impact assessment, transportation modal shift