Gasoline cars produce more carbonaceous particulate matter than modern filter-equipped diesel cars

Abstract

Carbonaceous particulate matter (PM), comprising black carbon (BC), primary organic aerosol (POA) and secondary organic aerosol (SOA, from atmospheric aging of precursors), is a highly toxic vehicle exhaust component. Therefore, understanding vehicle pollution requires knowledge of both primary emissions, and how these emissions age in the atmosphere. We provide a systematic examination of carbonaceous PM emissions and parameterisation of SOA formation from modern diesel and gasoline cars at different temperatures (22, −7 °C) during controlled laboratory experiments. Carbonaceous PM emission and SOA formation is markedly higher from gasoline than diesel particle filter (DPF) and catalyst-equipped diesel cars, more so at −7 °C, contrasting with nitrogen oxides (NOX). Higher SOA formation from gasoline cars and primary emission reductions for diesels implies gasoline cars will increasingly dominate vehicular total carbonaceous PM, though older non-DPF-equipped diesels will continue to dominate the primary fraction for some time. Supported by state-of-the-art source apportionment of ambient fossil fuel derived PM, our results show that whether gasoline or diesel cars are more polluting depends on the pollutant in question, i.e. that diesel cars are not necessarily worse polluters than gasoline cars.

Gas phase composition and secondary organic aerosol formation from gasoline direct injection vehicles investigated in batch and flow reactors: effects of prototype gasoline particle filters

“…Emissions of all cold-started vehicles, technologies and driving tests showed significant SOA formation upon photochemical oxidation (Figure 2b), in line with previous findings (( Platt et al, 2017); (Gordon et al, 2014); (Nordin et al, 2013)). This is consistent with the above observation that NMHC and NMOC emissions (determined by the PTR-ToF-MS, see Figure 2d OFR experiments typically result in higher SOA production than the SC experiments, which can be explained by higher OH exposure, leading to reaction of more precursor mass and higher OA loadings and hence an influence of partitioning effects ( (Pankow, 1994); (Donahue et al, 2006)), as discussed later (see SOA yield curve analysis, Figure 6).…”

Widespread Pollution From Secondary Sources of Organic Aerosols During Winter in the Northeastern United States

“…Laboratory-based studies find that residential wood combustion emits large amounts of aromatic VOCs, which is an additional source of SOA precursors in winter (Bruns et al, 2016), although many field studies do not report a net increase of ΔOA/ΔCO in biomass burning plumes (Cubison et al, 2011;Shrivastava et al, 2017). Gasoline vehicles emit several times more VOCs at colder temperatures and may therefore produce more SOA in winter but their CO emissions are also higher in winter (Platt et al, 2017). below 1-km altitude.…”

Local Arctic Air Pollution: A Neglected but Serious Problem

“…In this way, Arctic cities can be particularly vulnerable to pollution caused by the activities of the residents and local industry Tran & Mölders, 2011). Additionally, some local sources of pollution are stronger in wintertime because cold temperatures require more intense domestic heating and power generation, and mobile sources may be operating poorly due to extreme cold leading, for example, to increased emissions from automotive cold start (Platt et al, 2017). In contrast, during summer, near-constant sunlight and subsequent atmospheric heating causes stronger Murmansk, Anchorage, Reykjavik, and Norilsk are the largest settlements in terms of size of population in the region, while a number of small settlements with less than 10,000 inhabitants are visible in all regions and along the coasts of Iceland and western Greenland.…”