Particles Derived from Anthropogenic Sources

Epidemiology Studies Suggest an Association Between Urban Air Particles and Increased Mortality 

Marcel Dekker, Inc. 270Madison Ayoiiic. New Yoik, New Yodk 10016 

Risk Factors Associated with PM o-Induced increases in Mortaiity and Morbidity 

Possible Cellular Mechanisms of PM o-Induced Lung Injury 

Marcel Dekker, Inc. 270 Madison Avenue, New York, New York 10016 

---

The total rate of aerosol pnoduction is of the order of 2000 Tg/yr. Some comparisons are of interest. Anthropogenic sources, both direct and indirect, contribute about 15% to the global aerosol production rate. The percentage of direct emissions from anthropogenic sources is only about 20% of the total contribution, so that most of it derives from gas-to-particle conversion. With regard to natural aerosol formation, the percentage contribution of direct emissions is 60%, so that direct and secondary aerosol production are approximately equivalent. 

Atmospheric deposition of continentally-derived particles ( aerosols , dust ) is a major external input of iron to the oceans. In some open ocean areas, including the iron-limited subarctic Pacific, dust deposition is the dominant iron source to the surface layer. The atmospheric iron source is composed largely of aluminosilicate minerals derived from arid and semi-arid mid-latitude regions in the Northern Hemisphere [73-75] the exception to this rule is downwind of heavily populated areas, where a significant fraction of aerosol iron may originate from anthropogenic sources [76-78]. 

Globally, about half of all atmospheric sulfate is derived from combustion of fossil fuels and half from natural sources (Berner and Bemer 1987). It has been estimated that anthropogenic sources are responsible for 90% of the total atmospheric sulfur deposition in eastern North America, which occurs as dry deposition of SO2 gas and sulfate particles or dissolved in rain. The highest amounts of sulfate and nitrate in U.S. rain, which are found in the northeast [Fig. 8.7(a) and Fig. 8.7(b)], are... 

There are essentially three sources of radioactive elements. Primordial nuclides are radioactive elements whose half-lives are comparable to the age of our solar system and were present at the formation of Earth. These nuclides are generally referred to as naturally occurring radioactivity and are derived from the radioactive decay of thorium and uranium. Cosmogenic nuclides are atoms that are constantly being synthesized from the bombardment of planetary surfaces by cosmic particles (primarily protons ejected from the Sun), and are also considered natural in their origin. The third source of radioactive nuclides is termed anthropogenic and results from human activity in the production of nuclear power, nuclear weapons, or through the use of particle accelerators. 

Airborne particulate matter (PM) is a complex chemical mixture of extremely small solid particles and liquid droplets that can derive from both natural and anthropogenic sources (USEPA 2008 Vedal and Sullivan 2007). 

Particulate pollutants are emitted from many sources. Additionally, particles are formed in the atmosphere by both chemical and physical conversions from natural and anthropogenic gaseous substances. Particulate pollutants cover a size range from <10 nm to >100 pm. The major proportion of the aerosol below 1 pm is generally man-made, including sulfates from SO2 oxidation and carbon from vehicle exhausts, for example. Particles of a greater size are frequently natural (e.g., soil-derived, marine aerosol) but this division cannot be regarded as absolute. 

Particle precursor gases are emitted into the atmosphere either directly by natural and anthropogenic sources or by oxidation processes in the atmosphere. The most prominent precursor gas is probably sulfur dioxide (SO2). It is the precursor for particulate sulfates, such as sulfuric acid (H2SO4) or ammonium sulfate [(NH4)2S04]. Sulfur dioxide is directly emitted by natural sources (e.g., volcano emptions). Anthropogenic sources in industrial regions are mostly associated with combustion processes (e.g., coal combustion). Additional SO2 is derived from oxidation processes of dimethyl sulfide (DMS) over the oceans. Estimations of the global sulfur emissions from these sources are listed in Table 3. 

The number of elements in the anthropogenic factor also grows with decreasing particle size. The main elements are Pb, Sb, and Zn frequent elements are Mo, As, Sn, Cu, V, and S. The distance of Pellworm from any industrial emission sources does not enable further differentiation of the impact of the emissions without a key pattern derived... 

For the purposes of this discussion, it is reasonable to assume that the outdoor environment is the source of most of the anthropogenically derived substances (4) that are present in the indoor environment. The accumulation rates of species on indoor surfaces are related to the outdoor concentrations of these substances through the relationships among the indoor and outdoor concentrations and the indoor deposition velocities of these species. A substantial amount of data is available on outdoor concentrations (4-13). Simultaneous measurements of outdoor and indoor concentrations are less numerous. Very few measurements of indoor deposition velocities have been made. Estimated ratios of outdoor to indoor concentrations will be used that are based on field data, where available, or best judgments. From the limited experimental measurements, taking into account the relative variations in outdoor deposition velocities as a function of particle size, indoor deposition velocities will be estimated. Using these approximate indoor/outdoor ratios and deposition velocities, the indoor surface accumulation rates for substances contained in airborne particles can then be estimated from prevailing outdoor concentrations. 

---