Emission ultrafine particle

In the past half-decade, extensive studies have focused on aerosol nucleation in aircraft exhaust plumes [79]. This interest has brought attention to the formation of volatile aerosols that might eventually evolve into cloud condensation nuclei [80], Measurements of ultrafine particles reveal remarkably high abundances in jet wakes at very early times (within 1 second of emission) (e.g., [81]). As in the background atmosphere, the classical homogeneous nucleation theory has been applied to explain the number and size distribution of these volatile microscopic particles [82,83], However, while achieving some initial success, the theory has not been able to explain more recent, detailed observations. 

Morawska L, Ristovski Z, Jayaratne ER, Keogh DU, Ling X (2008) Ambient nano and ultrafine particles from motor vehicle emissions characteristics, ambient processing and implications on human exposure. Atmos Environ 42 8113-8138... 

Dahl A, Gharibi A, Swietlicki E, Gudmundsson A, Bohgard M, Ljungman A, Blomqvist G, Gustafsson M (2006) Traffic-generated emissions of ultrafine particles from pavement-tire interface. Atmos Environ 40 1314—1323... 

Schripp, T., Wensing, M., Uhde, E., Salthammer, T., He, C. and Morawska, L. (2008) Evaluation of ultrafine particle emissions from laser printers using emission test chambers. Environmental Science and Technology, 42, 4338-43. 

In addition to the formation of new secondary nanoparticles, there are also primary emissions of nanoparticles to the atmosphere, most importantly from high temperature combustion. While there are no published emissions inventories specifically for nanoparticles, Cass et al. (2000) estimate that approximately 85% of the mass of primary ultrafine particles (Dp <100 nm) in the Los Angeles area is emitted from combustion sources. On-road vehicles are estimated to account for approximately 40% of ultrafine particle mass. Similar results are reported for the United Kingdom, with a somewhat greater contribution (60% of total) from vehicles (Harrison et al. 2000). Observations in... 

Kane DB, Johnston MV (2000) Size and composition biases on the detection of individual ultrafine particles by aerosol mass spectrometry. Environ Sci Technol 34 4887-4893 Ka rcher B, Turco RP, Yu F, Danilin MY, Weisensdn DK, Miake-Lye RC, Busen R (2000) A unified model for ultrafine aircraft particle emissions. J Geophys Res 105 29379-29386 Kashchiev D (1982) On the relation between nucleation work, nucleus size, and nucleation rate. J Chem Phys 76 5098-5102... 

Concentration of particles in the air as well as particle size distributions can be considered either in terms of particle number or mass. In terms of number, the vast majority of airborne particles are in the ultrafine range. For example, in urban outdoor air where motor vehicle emissions are a dominant pollution source, over 80% of particulate matter in terms of number is in the ultrafine range [17]. Since outdoor particles contribute significantly to indoor particle concentrations, also in indoor air particle number concentration is usually dominated by the smallest particles. However, most of the mass of airborne particles is associated with large particles since the mass of ultrafine particles is often very small in comparison with the mass of larger particles. The particle surface area in turn is largest for particles somewhat above the ultrafine size range. 

Combustion particles are of complex chemistry, carrying most of the trace elements, toxins or carcinogens generated from the combustion process. Combustion of different types of fuels results in emissions of various trace elements which are present in the fuel material. In most cases there is not just one specific element that is related to the combustion of a particular fuel, but a source profile of elements [2]. For example, motor vehicle emissions contain Br, Ba, Zn, Fe and Pb (in countries where leaded petrol is used) and coal combustion results in the emission of Se, As, Cr, Co, Cu and Al. For comparison, the crustal elements include Mg, Ca, Al, K, Sc, Fe and Mn. Since most of the trace elements are nonvolatile, associated with ultrafine particles and less prone to chemical transformations, they often remain in the air for prolonged periods of time in the form in which they were emitted. 

Minutolo, P, D Anna, A., Commodo, M., PagUara, R., Toniato, G., and Accordini, C. "Emission of Ultrafine Particles from Natural Gas Domestic Burners." Environmental Engineering Science December 2008. 

Several studies in urban areas show that motor vehicular emissions constitute the most significant source of ultrafine (particle s aerodynamic diameter less than... 

Afshari A, Matson U, Ekberg L (2005) Characterization of indoor sources of fine and ultrafine particles a study conducted in a full-scale chamber. Indoor Air 15 141-150 Buonanno G, Morawska L, Stabile L (2009) Particle emission factors during cooking activities. Atmos Environ 43 3235-3242... 

Fushimi A, Hasegawa S, Takahashi K et al (2008) Atmospheric fate of nuclei-mode particles estimated from the number concentrations and chemical composition of particles measured at roadside and background sites. Atmos Environ 42 949-959 Gehin E, Ramalho O, Kirchner S (2008) Size distribution and emission rate measurements of fine and ultrafine particle from indoor human activities. Atmos Environ 42 8341-8352 Graham S, McCurdy T (2004) Developing meaningful cohorts for human exposure models. J Expo Anal Environ Epidemiol 14 23 3... 

Wigle DT, Arbuckle TE, Walker M, Wade MG, Liu S, Krewski D (2007) Environmental hazards evidence for effects on child health. J Toxicol Environ Health B 10 3-39 Wilson MR, Lightbody JH, Donaldson K, Sales J, Stone V (2002) Interactions between ultrafine particles and transition metals in vivo and in vitro. Toxicol Appl Pharmacol 184 172-179 Winer AM, Behrentz E (2005) Estimates of nitrous oxide emissions from mobn vehicles and the effects of catalyst composition and aging. Final report, submitted to the State of California Air Resources Board (Contract No. 02-313), p 216... 

Schauer JJ, Rogge WF, Hildemann LM et al (1996) Source apportionment of airborne particulate matter using organic compounds as tracers. Atmos Environ 30 3837-3855 Sinha P, Hobbs PV, Yokelson RJ et al (2003) Emissions of trace gases and particles from two ships in the southern Atlantic Ocean. Atmos Environ 37 2139-2148 Sioutas C, Delfino RJ, Singh M (2005) Exposure assessment for atmospheric ultrafine particles (UFPs) and implications in epidemiologic research. Environ Health Perspect 113 947-955... 

Figure 1. Measured aircraft ultrafine aerosol emissions are compared with equivalent model predictions. The aerosol emission index (El) is given as the total number of particles generated for each kilogram of fuel burned, at particle sizes exceeding d>5 nm or d> 14 nm (open and filled symbols, respectively). Data were collected in the SULFUR-5 field campaign. In the simulations (lines), different initial chemiion concentrations, nio, were assumed, as indicated in the legend at the left of the figure (the first number is the value of n in /cmJ, and the second is the lower particle size cutoff diameter, nm. From [84],...

The ultrafine range is usually composed of emissions from local combustion sources or particles generated by atmospheric photochemical activity that leads to homogeneous nucleation. The principal mechanism of decay of the ultrafine range is attachment to particles in the accumulation mode by diffusion. Neglecting the Brownian motion of the coarse particles compared with the fine particles, the fractional rate of decay of particles in the ultrafine range is given by (Chapter 7)... 

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