title: Evaluation of emission toxicity of urban bus engines: compressed natural gas and comparison with liquid fuels.
abstract: Emissions from a spark-ignition (SI) heavy-duty (HD) urban bus engine with a three-way catalyst (TWC), fuelled with compressed natural gas (CNG), were chemically analyzed and tested for genotoxicity. The results were compared with those obtained in a previous study on an equivalent diesel engine, fuelled with diesel oil (D) and a blend of the same with 20% vegetable oil (B20). Experimental procedures were identical, so that emission levels of the CNG engine were exactly comparable to the ones of the diesel engine. The experimental design was focused on carcinogenic compounds and genotoxic activity of exhausts. The results obtained show that the SI CNG engine emissions, with respect to the diesel engine fuelled with D, were nearly 50 times lower for carcinogenic polycyclic aromatic hydrocarbons (PAHs), 20 times lower for formaldehyde, and more than 30 times lower for particulate matter (PM). A 20-30 fold reduction of genotoxic activity was estimated from tests performed. A very high reduction of nitrogen oxides (NO(X)) was also measured. The impact of diesel powered transport on urban air quality, and the potential benefits deriving from the use of CNG for public transport, are discussed.
authors.affiliation: Istituto Superiore di Sanità, viale Regina Elena 299, 00161 Rome, Italy. lturrio@iss.it
authors.forename: Luigi
authors.initials: L
authors.lastname: Turrio-Baldassarri
authors.forename: Chiara Laura
authors.initials: CL
authors.lastname: Battistelli
authors.forename: Luigi
authors.initials: L
authors.lastname: Conti
authors.forename: Riccardo
authors.initials: R
authors.lastname: Crebelli
authors.forename: Barbara
authors.initials: B
authors.lastname: De Berardis
authors.forename: Anna Laura
authors.initials: AL
authors.lastname: Iamiceli
authors.forename: Michele
authors.initials: M
authors.lastname: Gambino
authors.forename: Sabato
authors.initials: S
authors.lastname: Iannaccone
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D000447:Aldehydes / Q000032:analysis; D004784:Environmental Monitoring; D005579:Fossil Fuels; D005742:Gasoline; D006841:Hydrocarbons, Aromatic / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D018986:Motor Vehicles; D009152:Mutagenicity Tests; D010316:Particle Size; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics; D001335:Vehicle Emissions / Q000032:analysis / Q000633:toxicity*
chemical_list: D000393:Air Pollutants; D000447:Aldehydes; D005579:Fossil Fuels; D005742:Gasoline; D006841:Hydrocarbons, Aromatic; D011084:Polycyclic Aromatic Hydrocarbons; D001335:Vehicle Emissions