Environmental and Health Impacts of the Change of NMHCs Caused by the Usage of Clean Alternative Fuels for Vehicles

Vehicle exhaust and roadside air samples were collected at Guangzhou, Shenzhen and Chengdu in China, where liquefied petroleum gas (LPG), liquefied natural gas (LNG) and compressed natural gas (CNG)-common fuel alternatives for vehicles worldwide-are used, respectively. The emission characteristics, ozone formation potential (OFP) and health risks of nonmethane hydrocarbons (NMHCs) in conventional and clean alternative fuel exhaust emitted by vehicles were assessed to explore the environmental and health effects from the change in NMHCs due to using clean alternative fuels. Our results indicate that the fuel type significantly impacted the composition of the roadside air. The OFP values for the total NMHCs were much lower in the CNG (2.5 ppmv), LNG (4.7 ppmv) and diesel (4.5 ppmv) exhaust than in the gasoline (94.3 ppmv) and LPG (23.1 ppmv) exhaust, indicating that using CNG and LNG may effectively reduce O3 formation due to vehicle exhaust. Additionally, the hazard quotient (HQ), hazard index (HI) and cancer risk (Risk) of NMHC species in the vehicle exhaust were calculated. Both the HI and Risk of these species in the exhaust from gasoline-powered vehicles greatly exceeded those from the other four types of vehicles, suggesting that using clean alternative fuels instead of gasoline benefits human