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Particle diameter (urn)

FIGURE 2.13 Calculated deposition of particles in various regions of the lung for polydisperse aerosol (o% = 2.5; see Chapter 9.A.2) (adapted from Yeh et al., 1996).

Sources excluding fugitive dust

Non-Road Engines and Vehicles 15%

Fuel Combustion -Other 15%

Other Industrial Processes 13%

Fuel Combustion -

Industrial

Non-Road Engines and Vehicles 15%

Other Industrial Processes 13%

Fuel Combustion -

Industrial

Miscellaneous 19%

All Other 32%

Miscellaneous 19%

All Other 32%

Fugitive dust sources

Paved Roads 9%

All Other 2%

Construction 14%

Unpaved Roads 38%

Paved Roads 9%

Construction 14%

All Other 2%

Unpaved Roads 38%

Agricultural Crops 17%

Natural Sources 20%

FIGURE 2.15 Sources of PM,„ emissions in the United States in 1996 (a) excluding fugitive dust sources; transportation sources accounted for 21% of the total, and (b) fugitive dust sources (adapted from EPA, 1997).

Agricultural Crops 17%

Natural Sources 20%

FIGURE 2.15 Sources of PM,„ emissions in the United States in 1996 (a) excluding fugitive dust sources; transportation sources accounted for 21% of the total, and (b) fugitive dust sources (adapted from EPA, 1997).

carried inland. While more than 50% tend to be >3 ftm, in diameter, recent studies suggest that there are also a number of particles produced in the submicron size range as well (see Chapter 9). The chemical composition of sea-generated particles includes the elements found in seawater (primarily chlorine, sodium, sulfur, magnesium, potassium, and calcium) and organic materials, perhaps including viruses, bacteria, and so on.

Biological emissions of particles may occur from plants and trees; additionally, volatile organics such as isoprene and terpenes can react in the air to form small particles.

Volcanic eruptions are highly variable but can pro duce large amounts of particles. For example, for the St. Augustine (Alaska) eruption in 1976, particulate emissions over the period of 1 year were estimated to be ~ 6 X 10ft metric tons (Stith et al., 1978). Wildfires and biomass burning also produce significant particulate matter, most of it in the respirable size range from ~ 0.1 to 1 /iim. Elemental carbon and organics form the majority of these particles, with some minerals also being present.

6. Lead

Prior to the introduction of unleaded fuels, gasoline combustion in motor vehicles was by far the greatest

3 Chemical and

Allied Products

Fuel Combustion - Other 11%

All Other 4%

Non-Road Engines Metals I anc' Vehicles

Processing I / iP'i~a'jyAi'crait';

Waste Disposal 17%

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