Particulate size distribution

EPA will closely examine particulate size distribution in particulate emission trades because finer particulates disperse more widely, remain in the air longer, and frequently are associated with more adverse health effects. 

Alves, C, Pio, C, and Duarte, A. C. (2000). Particulate size distributed organic compounds in a forest atmosphere. Environ. Sci. Technol. 34,4287 4293. 

The following sections describe, in turn, particulate size distributions, coagulation and condensation processes, production mechanisms, chemical composition, removal from the atmosphere, and the tropospheric budget of the aerosol. 

Fig. 7-16. Particulate size distributions at the summit of Mt. Schauinsland (1250 m a.s.l.), May 16-17, 1978. The variation in the Aitken size range is indicative of gas-to-particle conversion during periods of sunlight, and absence of gas-to-particle conversion at night. [Adapted from Haaf and Jaenicke (1980).]...

C2 is the cross-sectional surface area shape factor, n(Z) is the particulate size distribution function dN/dl, and Kext is the extinction eflBciency (a function of A., the wavelength of the incident light, I, the particulate size, and m, the particulate refractive index relative to the surrounding medium). Thus, the contribution of any given size fraction of the distribution to the extinction coeflBcient is partly a function of the size frequency distribution as shown by the expression... 

Dust control. Small plutonium oxide particulates may become airborne and result in inhalation dose. Particulate size distribution at various stages and aerosol transport are subjects for careful study. Equipment and process designs can be used to control airborne particulate, such as setting up various pressure control zones in ventilation design, installing HEPA filtration systems, and installing area airborne particulate monitors. 

Impactor samplers, which permit a broader range of measurable particulate size distributions, are constructed so that air entering at high flow rates encounters a series of trapping surfaces and particles are trapped based on size. First trapped are the coarsest particles followed sequentially by smaller and smaller fractions. The cascade samplers typically allow fractionations within narrow ranges, such as 0.01—0.1 (im (Dzubay et al., 1976). 

Particulate size distribution into cyclone and/or multiclone. 

Figure 11.1 Diesel particulate size distribution. Solid line number distribution. Broken line mass distribution. Adapted from Majewski and Khair. ...

Yang, H.H., L.T. Hsieh, and S.K. Cheng, Determination of atmospheric nitrate particulate size distribution and dry deposition velocity for three distinct areas. Chemosphere, 2005. 60(10) 1447-1453. 

The environmental processes of transformation, transport, and deposition of lead are prominently influenced by the particle sizes. Size distributions of lead particulates have been studied to determine their relation to numerous evironmental questions [21, 27, 28, 34]. These investigations have determined that the smaller lead particles (less than 0.5 pm in diameter) make up the largest fraction of those exhausted from internal combustion engines, with mean particle size decreasing with increasing speed. There is little modification of the characteristics of the lead particulate size distribution as a result of non-precipitative atmospheric mechanisms. 

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