Estimating the health benefits from natural gas use in transport and heating in Santiago, Chile Marcelo Mena-Carrasco a, ⁎, Estefania Oliva a , Pablo Saide b , Scott N. Spak c , Cristóbal de la Maza d , Mauricio Osses a, e , Sebastián Tolvett e , J. Elliott Campbell f , Tsao es Chi-Chung Tsao f , Luisa T. Molina g a Center for Sustainability Research, Universidad Andrés Bello, Chile b Center for Global and Regional Environmental Research, University of Iowa, USA c Public Policy Center, The University of Iowa, USA d Chilean Ministry of the Environment, Chile e International Sustainable Systems Research Center, USA f School of Engineering, University of California at Merced, USA g Molina Center for Energy and Environment, USA abstract article info Article history: Received 3 February 2012 Received in revised form 10 April 2012 Accepted 13 April 2012 Available online 15 May 2012 Keywords: PM2.5 WRF-chem Health benefits Santiago Wood burning Compressed natural gas Chilean law requires the assessment of air pollution control strategies for their costs and benefits. Here we em- ploy an online weather and chemical transport model, WRF-Chem, and a gridded population density map, LANDSCAN, to estimate changes in fine particle pollution exposure, health benefits, and economic valuation for two emission reduction strategies based on increasing the use of compressed natural gas (CNG) in Santiago, Chile. The first scenario, switching to a CNG public transportation system, would reduce urban PM2.5 emissions by 229 t/year. The second scenario would reduce wood burning emissions by 671 t/year, with unique hourly emission reductions distributed from daily heating demand. The CNG bus scenario reduces annual PM2.5 by 0.33 μg/m 3 and up to 2 μg/m 3 during winter months, while the residential heating scenario reduces annual PM2.5 by 2.07 μg/m 3 , with peaks exceeding 8 μg/m 3 during strong air pollution episodes in winter months. These ambient pollution reductions lead to 36 avoided premature mortalities for the CNG bus scenario, and 229 for the CNG heating scenario. Both policies are shown to be cost-effective ways of reducing air pollution, as they target high-emitting area pollution sources and reduce concentrations over densely populated urban areas as well as less dense areas outside the city limits. Unlike the concentration rollback methods commonly used in public policy analyses, which assume homogeneous reductions across a whole city (including homoge- neous population densities), and without accounting for the seasonality of certain emissions, this approach ac- counts for both seasonality and diurnal emission profiles for both the transportation and residential heating sectors. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Fuels are typically chosen based on technical attributes (yields, effi- ciencies, etc.) and price. However environmental effects are often over- looked, which are quantified as externalities. These can be quite large, sometimes doubling or tripling the direct cost of the fuel as in the case of coal, for example (Epstein et al., 2011). Many of these externalities are related to increases in adverse health effects due to acute and chron- ic exposure to particulate matter (PM), including increased mortality, respiratory symptoms, and asthma attacks, among others (Dockery et al., 1993; Pope et al., 1995; Seaton et al., 1995; Samet et al., 2000; Pope and Dockery, 2006). Chile incorporated social and economic evaluation for environmental regulations when the environmental in- stitutions were created, with a mandate to consider cost effectiveness in their environmental regulations (Ministry of the Environment, 2007; Katz et al., 2010). Cost and benefit analyses are routinely used in support of the development of regulatory instruments such as air quality and emission standards, as well as air quality attainment plans. These evolved in sophistication, from rollback methods to the empirical factors that relate changes in emissions and concentrations (Chang and Winstock, 1975; DICTUC, 2011) used to support the Chilean PM2.5 (particulate matter of less than 2.5 μm in aerodynamic diameter) air quality standard (Cifuentes, 2010). The recently approved Chilean power plant emissions standard (MMA, 2011) included the combina- tion of an electric tariff model to project future emissions with an atmo- spheric dispersion model to explicitly calculate benefits from reducing primary and secondary PM under regulatory scenarios (KAS, 2009). Santiago, Chile, has benefited from using cost–benefit analysis to support the measures in their pollution attainment plans. Since 1989, Science of the Total Environment 429 (2012) 257–265 ⁎ Corresponding author. Tel.: + 56 26618230. E-mail address: mmena@unab.cl (M. Mena-Carrasco). 0048-9697/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.scitotenv.2012.04.037 Contents lists available at SciVerse ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv