Estimating the health benefits from natural gas use in transport and heating in Santiago, Chile.

Chilean law requires the assessment of air pollution control strategies for their costs and benefits. Here we employ 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/m³ and up to 2 µg/m³ during winter months, while the residential heating scenario reduces annual PM2.5 by 2.07 µg/m³, with peaks exceeding 8 µg/m³ 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 homogeneous population densities), and without accounting for the seasonality of certain emissions, this approach accounts for both seasonality and diurnal emission profiles for both the transportation and residential heating sectors.

Characteristics of diesel truck emission in China based on portable emissions measurement systems.

Seventy-five diesel vehicles were measured in China using a portable emissions measurement system (PEMS). Particular matter (PM) emission factors and gaseous emission factors for Euro 0 (E0), Euro 1 (E1), Euro 2 (E2), and Euro 3 (E3) trucks were obtained under highway, urban, and rural driving conditions. Vehicle emission regulations in China have successfully reduced carbon monoxide (CO), hydrocarbons (HC) and PM by 62, 56, and 72% on average. Most of the emission reductions were achieved when the control technology went from E0 to E1 in Xi'an, and E2 to E3 in Beijing, which resulted in PM reductions of 79% associated with highway driving and 60% associated with urban or rural driving. Emission levels of oxides of nitrogen (NO(X)) were not improved from previous emission control steps. Compared with Xi'an, the emission rate is lower in Beijing, which is strong evidence of the effectiveness of the present comprehensive emission control strategy in Beijing. Emissions were grouped into driving bins that corresponded to the energy demand placed on the vehicles. By using this binning approach, it was found that E3 trucks were successfully controlling the high emission rates in aggressive driving bins, which led to the low average emission for E3 trucks.