Emission Rates and Comparative Chemical Composition from Selected In-Use Diesel and Gasoline-Fueled Vehicles

TLDR

Emission samples for toxicity testing and detailed chemical characterization were collected from gasoline‑ and diesel‑fueled in‑use vehicles on a Unified Driving Cycle chassis dynamometer, including various particle emitters, new‑technology gasoline cars, current‑technology diesel cars, and a high‑PM diesel, with speciated organic analysis performed on fuels and lube oils after testing. Total PM emission rates spanned from below 3 mg/mi to over 700 mg/mi, and emission compositions varied with fuel type, vehicle maintenance level, and ambient temperature, with oil‑burning gasoline vehicles emitting higher concentrations of PAH that matched the PAH found in their lube oils.

Abstract

Abstract Emission samples for toxicity testing and detailed chemical characterization were collected from a variety of gasoline- and diesel-fueled in-use vehicles operated on the Unified Driving Cycle on a chassis dynamometer. Gasoline vehicles included normal particle mass (particulate matter [PM]) emitters (tested at 72 and 30°F), “black” and “white” smokers, and a new-technology vehicle (tested at 72 °F). Diesel vehicles included current-technology vehicles (tested at 72 and 30°F) and a high PM emitter. Total PM emission rates ranged from below 3 mg/mi up to more than 700 mg/mi for the white smoker gasoline vehicle. Emission rates of organic and elemental carbon (OC/EC), elements (metals and associated analytes), ions, and a variety of particulate and semi-volatile organic compounds (polycyclic aromatic hydrocarbons [PAH], nitro-PAH, oxy-PAH, hopanes, and steranes) are reported for these vehicles. Speciated organic analysis also was conducted on the fuels and lube oils obtained from these vehicles after the emissions testing. The compositions of emissions were highly dependent on the fuel type (gasoline vs. diesel), the state of vehicle maintenance (low, average, or high emitters; white or black smokers), and ambient conditions (i.e., temperature) of the vehicles. Fuel and oil analyses from these vehicles showed that oil served as a repository for combustion byproducts (e.g., PAH), and oil-burning gasoline vehicles emitted PAH in higher concentrations than did other vehicles. These PAH emissions matched the PAH compositions observed in oil.