Two-stroke scooters are a dominant source of air pollution in many cities

Platt, Stephen Matthew; Haddad, Imad El; Pieber, Simone M.; Huang, Ru‐Jin; Zardini, Alessandro; Clairotte, Michaël; Suarez-Bertoa, Ricardo; Barmet, Peter; Pfaffenberger, L.; Wolf, Robert; Slowik, Jay G.; Fuller, S. J.; Kalberer, Markus; Chirico, R.; Dommen, Josef; Astorga, Covadonga; Zimmermann, Ralf; Marchand, Nicolas; Hellebust, Stig; Temime-Roussel, Brice; Baltensperger, Urs; Prévôt, Andrê S. H.

doi:10.1038/ncomms4749

Cited by 138 publications

(91 citation statements)

References 27 publications

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“…The PM 2.5 pollution particles in air have complicated compositions including inorganic matter (such as SiO 2 , SO 4 2 À and NO 3 À ) and organic matter (such as, organic carbon and elemental carbon) from diverse sources including soil dust, vehicular emission, coal combustion, secondary aerosols, industrial emission and biomass burning 1,[18][19][20][21] . The behaviour of PM particles are different because of their chemical compositions, morphologies and mechanical properties 15 .…”

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confidence: 99%

Transparent air filter for high-efficiency PM2.5 capture

et al. 2015

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Particulate matter (PM) pollution has raised serious concerns for public health. Although outdoor individual protection could be achieved by facial masks, indoor air usually relies on expensive and energy-intensive air-filtering devices. Here, we introduce a transparent air filter for indoor air protection through windows that uses natural passive ventilation to effectively protect the indoor air quality. By controlling the surface chemistry to enable strong PM adhesion and also the microstructure of the air filters to increase the capture possibilities, we achieve transparent, high air flow and highly effective air filters of B90% transparency with 495.00% removal of PM 2.5 under extreme hazardous air-quality conditions (PM 2.5 mass concentration 4250 mg m À 3 ). A field test in Beijing shows that the polyacrylonitrile transparent air filter has the best PM 2.5 removal efficiency of 98.69% at high transmittance of B77% during haze occurrence.

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confidence: 99%

Transparent air filter for high-efficiency PM2.5 capture

et al. 2015

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“…Here, we term such aerosols delayed primary aerosols, because particle precursors exist already in the undiluted exhaust and the amounts and characteristics of the resulting atmospheric particulate matter do not depend significantly on atmospheric processing or atmospheric photochemistry. In the secondary aerosol formation process driven by atmospheric photochemistry, volatile gaseous compounds emitted by traffic are chemically transformed in the atmosphere to less volatile species, enabling and enhancing secondary aerosol particle formation via condensation, as well as new particle formation (20)(21)(22) Whereas the primary and delayed primary particle emissions affect mostly the air quality near the emission source, the effects of the secondary processes are more important on a regional scale.…”

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confidence: 99%

Traffic is a major source of atmospheric nanocluster aerosol

Rönkkö

Kuuluvainen

Karjalainen

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

202

132

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In densely populated areas, traffic is a significant source of atmospheric aerosol particles. Owing to their small size and complicated chemical and physical characteristics, atmospheric particles resulting from traffic emissions pose a significant risk to human health and also contribute to anthropogenic forcing of climate. Previous research has established that vehicles directly emit primary aerosol particles and also contribute to secondary aerosol particle formation by emitting aerosol precursors. Here, we extend the urban atmospheric aerosol characterization to cover nanocluster aerosol (NCA) particles and show that a major fraction of particles emitted by road transportation are in a previously unmeasured size range of 1.3-3.0 nm. For instance, in a semiurban roadside environment, the NCA represented 20-54% of the total particle concentration in ambient air. The observed NCA concentrations varied significantly depending on the traffic rate and wind direction. The emission factors of NCA for traffic were 2.4·10 15 (kg fuel ) −1 in a roadside environment, 2.6·10 15 (kg fuel ) −1 in a street canyon, and 2.9·10 15 (kg fuel ) −1 in an on-road study throughout Europe. Interestingly, these emissions were not associated with all vehicles. In engine laboratory experiments, the emission factor of exhaust NCA varied from a relatively low value of 1.6·10 12 (kg fuel ) −1 to a high value of 4.3·10 15 (kg fuel ) −1 . These NCA emissions directly affect particle concentrations and human exposure to nanosized aerosol in urban areas, and potentially may act as nanosized condensation nuclei for the condensation of atmospheric low-volatile organic compounds.nanocluster aerosol | atmospheric aerosol | combustion-derived nanoparticles | air pollution | traffic emission D etailed characterization of aerosol sources is required to understand climate impacts and health effects of atmospheric aerosols, as well as to develop technologies and policies capable of mitigating air pollution in urbanized areas. In densely populated areas, one of the most significant source of particles is traffic (1, 2). Owing to their small size and complicated chemical and physical characteristics (3-6), atmospheric particles resulting from traffic emissions pose a significant risk to human health (7-12), and also contribute to anthropogenic forcing of climate (13,14). Previous research on vehicular emissions has demonstrated the presence of soot and ash (3, 15) and solid sub-10-nm core particles (4-6) in primary emissions from vehicles and engines and their variation, depending on vehicle technologies (4, 6), the properties of fuels and lubricant oils (15, 16), and driving conditions (15-17). In addition to particles, exhaust typically contains species that reside in the gaseous phase in the undiluted high-temperature exhaust (5, 18, 19) but condense or even nucleate to the particle phase immediately after the exhaust is released to the atmosphere. Here, we term such aerosols delayed primary aerosols, because particle precursors exist already in the u...

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“…The dominance of the RO 2 -NO or RO 2 -RO 2 reactions is driven by the NO levels. Based on (Platt et al, 2014), RO 2 radicals predominantly react with NO, when the concentration of NO is higher than only 1 ppb in the SC. Before starting the SC aging by injecting HONO and initiating photo-chemistry, we titrate NO present in the SC to NO 2 using O 3 .…”

Section: Cn) Due To Challenges In Its Quantification Without Proper mentioning

confidence: 99%

“…This leaves about 35% additional carbon to be attributed to other molecules. While both aromatic ( (Odum et al, 1997); (Ng et al, 2007b); (Hildebrandt et al, 2009); (Loza et al, 2012); (Platt et al, 2014)) and aliphatic (especially alkanes) ( (Lim and Ziemann, 2005); (Loza et al, 2014)) species are found in vehicle exhaust and may form SOA, aliphatic species do so only if their carbon chain is 20 sufficiently long and does not substantially fragment during reaction. Short-chain alkanes (<C 8 ) are expected to have only low SOA yields at typical ambient OA levels (Jordan et al, 2008).…”

Section: Soa Yield Of Vehicle Exhaust Vs Single Precursorsmentioning

confidence: 99%

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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

Pieber

Kumar

Klein

et al. 2017

Preprint

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Abstract. Gasoline direct injection (GDI) vehicles have recently been identified as a significant source of carbonaceous aerosol, of both primary and secondary origin. Here we investigated primary emissions and secondary organic aerosol (SOA) formation from GDI vehicle exhaust for multiple vehicles and driving test cycles, and novel GDI after-treatment systems.Emissions were characterized by proton transfer reaction time-of-flight mass spectrometry (gaseous non-methane organic 15 compounds, NMOCs), aerosol mass spectrometry (sub-micron non-refractory particles), and light attenuation measurements (equivalent black carbon (eBC) determination using Aethalometer measurements) together with supporting instrumentation.We evaluated the effect of retrofitted prototype gasoline particle filters (GPFs) on primary eBC, organic aerosol (OA), NMOCs, as well as SOA formation. Two regulatory driving test cycles were investigated, and the importance of distinct phases within these cycles (e.g. cold engine start, hot engine start, high speed driving) to primary emissions and secondary 20 products was evaluated. Atmospheric processing was simulated using both the PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow reactor (OFR). GPF retrofitting was found to greatly decrease primary particulate matter (PM) through removal of eBC, but showed limited partial removal of the minor POA fraction, and had no detectable effect on either NMOC emissions (absolute emission factors or relative composition) or SOA production. In all tests, overall primary and secondary PM and NMOC emissions were dominated by the engine cold start, i.e. before thermal activation of 25 the catalytic after-treatment system. Differences were found in the bulk compositional properties of SOA produced by the OFR and the SC (O:C and H:C ratios), while the SOA yields agree within our uncertainties, with a tendency for lower SOA yields in SC experiments. A few aromatic compounds are found to dominate the NMOC emissions (primarily benzene, toluene, xylene isomers and C3-benzenes). A large fraction (> 0.5) of the SOA production was explained by those compounds, based on investigation of reacted NMOC mass and comparison with SOA yield curves of toluene, o-xylene and 30 1,2,4-trimethylbenzene determined in our OFR within this study. Remaining differences in the obtained SOA yields may Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-942 Manuscript under review for journal Atmos. Chem. Phys. Atmos. Chem. Phys. Discuss., https://doi

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Two-stroke scooters are a dominant source of air pollution in many cities

Cited by 138 publications

References 27 publications

Transparent air filter for high-efficiency PM2.5 capture

Transparent air filter for high-efficiency PM2.5 capture

Traffic is a major source of atmospheric nanocluster aerosol

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

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