Particulate air pollutants, gaseous and

This discussion was mainly drawn from research on the global distributions of gaseous and particulate air pollutants sponsored at Stanford Research Institute by the American Petroleum Institute. 

Pollution. Gaseous and particulate air pollution is a fact of life. Although it may be invisible to the human eye, its detrimental effects on a fragile wooden object may be very visible. Aided by an uncontrolled warm, humid microclimate in the display case, pollution chemically degrades wood and can diminish the aesthetics of an artifact by discoloration or decay. 

Peterson, T, W, Seinfeld, J. H., "Mathematical Model for Transport, Interconversion and Removal of Gaseous and Particulate Air Pollutants - Application to the Urban Plume, Atmospheric Environment (1978) 12, xxx... 

Mass concentration of inhalable particles is only one measure of a complex mixture of gaseous and particulate air pollution to which people are exposed. PM 10 includes a wide array of potentially toxic chemical species. Therefore, it is presumptuous to assign these observed health effects solely to the mass concentration of particulates. On the other hand, the consistency of these observed effects across so many communities suggests that, lacking an explicit hypothesis, these associations are assigned to a nonspecific definition of inhalable or fine particle concentrations common to urban areas. 

Aerosol Dynamics. Inclusion of a description of aerosol dynamics within air quaUty models is of primary importance because of the health effects associated with fine particles in the atmosphere, visibiUty deterioration, and the acid deposition problem. Aerosol dynamics differ markedly from gaseous pollutant dynamics in that particles come in a continuous distribution of sizes and can coagulate, evaporate, grow in size by condensation, be formed by nucleation, or be deposited by sedimentation. Furthermore, the species mass concentration alone does not fliUy characterize the aerosol. The particle size distribution, which changes as a function of time, and size-dependent composition determine the fate of particulate air pollutants and their... 

Fig. 15-1. CaUfomia South Coast Air Basin stationary monitoring locations operating during 1991. (L.A., Los Angeles). Source California Air Resources Board, "Summary of 1991 Air Quality Data, Gaseous and Particulate Pollutants," Vol. 23, 1991.

CaUfomia Air Resources Board, "Summary of 1991 Air Quality Data, Gaseous and Particulate Pollutants." CaUfomia Air Resources Board, Sacramento, 1991. 

Considerable work has been done on the behavior of pollutant species at air-water and air-soil interfaces. For example, wet and diy deposition measurements of various gaseous and particulate species have been made over a wide range of atmospheric and land-cover conditions. Still, the problem is of such complexity that species-dependent and particle-size-dependent rates of transfer from the atmosphere to water and soil surfaces are not completely understood. There is much to be learned about pollutant transfer at water-soil interfaces. Concern about groundwater contamination by mineral... 

In addition to the criteria pollutants, a wide variety of trace gaseous and particulate species are present in the polluted troposphere (Finlayson-Pitts and Pitts, 1997). Table 2.9 shows some of these gaseous noncriteria pollutants identified in photochemical air pollution and gives typical concentrations under conditions ranging from those in remote areas to severely polluted urban air (see also Chapter 11). 

In addition to the above criteria pollutants, one finds in the air a host of other gaseous and particulate pollutants, generally designated as hazardous air pollutants (HAPs), or simply air toxics. The US EPA identified 189 HAPs. Of course, not all HAPs are related to fossil fuel usage. Examples of fossil fuel HAPs are products of incomplete combustion (PIC), volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), toxic metals (e.g., Hg, Pb, Cd,... 

Once the inhalation exposure questions have been identified, the specifications for each personal monitor must be determined and the monitor must be validated for the contaminant being measured. Table I, updated from Samet et al. (14), identifies currently available personal monitors, and Table II, taken from an Environmental Protection Agency (EPA) report (15), shows the projected needs in the 1990s. There are a number of opportunities for research on personal monitors Table II indicates that relatively few commercial units are currently available for either particulate or gas-phase species. For compounds such as polycyclic aromatic hydrocarbons (PAHs), a two-stage sampler is required because some PAHs exist simultaneously in the gaseous and particulate phase (16). Consequently, research must be ranked with respect to the significance of the air pollution problem, and the technological developments required to provide reliable samplers must be defined. 

Abstract Gaseous and particulate emissions from vehicles represent a major source of atmospheric pollution in cities. Recent research shows evidence of, along with the primary emissions from motor exhaust, important contributions from secondary (due to traffic-related organic/inorganic gaseous precursors) and primary particles due to wear and resuspension processes. Besides new and more effective (for NO emissions) technologies, non-technological measures from local authorities are needed to improve urban air quality in Europe. 

Semi-volatile Organic Pollutants in the Gaseous and Particulate Phases in Urban Air... 

Emission standards are govemmentally promulgated limits on the emission of a pollutant from a process. There are limits on the emission of specific gaseous, vapor, and particulate pollutants from any process and on their emission from specific processes. Some countries (e.g., the United States) officially promulgate and publish their emission standards for new sources for a number of processes and for hazardous pollutants from ary process (Table XI). In the United States, emission standards for existing sources are promulgated and published by state and local air pollution control authorities. Some countries (e.g., Russia) do not promulgate or publish emission standards. 

Deposition includes dry and wet processes by which gaseous pollutants and aerosols are removed from the atmosphere [39]. Dry deposition is the transport of gaseous and particulate species from the atmosphere onto underlying surfaces. The intensity of dry deposition is expressed by the vertical flux, F, which represents the amount of pollutants deposited on a unit surface area per unit time. The proportionality constant between flux and concentration in the air of the surface layer, C, has units of length per unit time and is named the deposition velocity, v ... 

Particulate carbon as soot, carbon black, coke, and graphite originates from auto and truck exhausts, heating furnaces, incinerators, power plants, and steel and foimdry operations, and composes one of the more visible and troublesome particulate air pollutants. Because of its good adsorbent properties, carbon can be a carrier of gaseous and other particulate pollutants. Particulate carbon surfaces may catalyze some heterogeneous atmospheric reactions, including the important conversion of SO2 to sulfate. 

Air quality has become a serious issue in some areas, such as Sao Paulo and Cubatao cities, where this problem assumed critical proportions, with serious damage to water resources, vegetation and population (CETESB, 1981 Kucinski, 1982 Monteleone Neto, 1982 and Queiroz Neto et al.,1984).The serious health implication of air pollution in these areas has meant that gaseous and particulate matter has been researched and controlled more fully than has acidic precipitation. 

E. A. Wolfe, Gas Flow Rate and Particulate Matter Determination of Gaseous Effluents, Bay Area Air Pollution Control District 1480, San Erancisco, Calif., 1961. 

---