Everything you wish you didn't know about TSP And PM-10

Description of Particulate Matter (TSP and PM-10)
Characteristics: Not all air pollutants are gases. Particulate matter is a collective term used for very small solid and/or liquid particles found in the atmosphere. While individual particles cannot be seen with the naked eye, collectively they can appear as black soot, dust clouds or grey hazes. Particulate matter may be generated by natural processes (e.g., pollen, bacteria, viruses, fungi, mold, yeast, salt spray, soil from erosion) or through human activities, including diesel trucks, power plants, wood stoves and industrial processes. Individual particles vary considerably in size, geometry, chemical composition and physical properties. The effect of particulates on human health and the environment varies with the physical and chemical makeup of the particulates.
One of the major characteristics of particulate matter is particle size. Particles can range in size from 0.005 - 500 micrometers or microns (um), which is equal to one-millionth (10 -6) of a meter. Particles less than 2.5 microns in diameter are known as "fine" particles; those larger than 2.5 microns are known as "coarse" particles. Fine particles with diameters of less than 1 um, move like gases. Because of their low settling velocities, fine particles may be transported 1,000 kilometers or more from their source. Under the influence of gravity, larger particles do not remain suspended and tend to settle out of the air, sometimes creating localized areas of high particle disposition.
Total suspended particulate matter (TSP) refers to all particles in the atmosphere. TSP was the first indicator used to represent suspended particles in the ambient air.
In July 1987, EPA began using a new indicator, PM-10, which includes only those particles with aerodynamic diameter smaller than 10 um. Ten microns is approximately one seventh the diameter of a human hair. This fraction of TSP is responsible for most of the adverse human health effects of particulate matter because of the particles' ability to reach the lower regions of the respiratory tract. Recent data suggests that particles 2.5 um or smaller may pose the greatest threat to human health because, for the same mass, they absorb more toxic and carcinogenic compounds than larger particles and penetrate more easily deep into the lungs. EPA is considering adopting a new standard for PM-2.5 to better address the potential health problems associated with these tiny particles.
Sources: Particles are either emitted directly into the atmosphere or produced in the atmosphere from the physical and chemical transformation of other vaporous or gaseous pollutants.
The major sources of atmospheric particulates are fossil-fuel combustion (which produces ash and soot), industrial processes (involving metals, fibers, etc.), transportation, wind and soil erosion (producing fugitive dust), and photochemical reactions (complex chain reactions between sunlight and gaseous pollutants). Fugitive dust and particles from industrial processes tend to be larger in size ( > 1 um). Particles from combustion and photochemical reactions are usually smaller in size ( < 1 um).
Because of the large number of sources, particulate matter may contain hundreds of different chemical elements. Fine particles (PM-10) may contain substantial quantities of sulfate, ammonium, nitrate, elemental carbon and condensed organic compounds. Carcinogenic compounds and heavy metals such as arsenic, selenium, cadmium and zinc are also concentrated in these particles. Larger particles, such as soil particles, fly ash, road aggregate, wood ash, soot and pollen are composed primarily of minerals, including silicon, aluminum, potassium, iron, calcium and other alkaline elements.
Concentration: Particle concentrations are expressed as ug/m3 (micrograms of particle per cubic meter of ambient air). Under very clean atmospheric conditions, the TSP level can be as low as 0-10 ug/m3. In a very dirty environment, TSP concentration can be as high as 1,500 ug/m3. In monitoring studies of more than 1,400 sampling sites across the United States, annual arithmetic mean TSP values ranged from nine to 288 ug/m3. The lowest values were reported at remote sites, while high values were associated with industrial settings.
Health Effects: Studies of air pollution on health have linked particulate matter (alone or in combination with other air pollutants) with a number of significant health effects. These include increased mortality and aggravation of existing respiratory and cardiovascular disease, as evidenced by increased hospitalization, school absences and lost work days.
The health effects of atmospheric particulate matter are related to its ability to penetrate the respiratory system. In general, respiratory defense mechanisms are able to remove 99 percent of particles larger than 10 um from the inhaled air stream. Smaller particles ( > 2.5 um), called "inhalable," can cling to protective mucous and removed in the upper respiratory system. Fine particles ( < 2.5 um), also called "respirable," can enter the lungs and end up in lung capillaries and air sacs (alveoli).
In the lungs, particulates slow the exchange of oxygen and carbon dioxide in the blood, causing shortness of breath. The heart may be strained because it must work harder to compensate for oxygen loss. Laboratory studies show that high concentrations of components of particulate matter cause persistent cough, phlegm, wheezing and physical discomfort. Particulate matter can also alter the immune system and affect removal of foreign material from the lung (i.e., bacteria and pollen).
Absorbed substances of particular concern include sulfur oxides (SOx), chlorinated hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and heavy metals such as lead, cadmium, zinc and mercury. Soot, fly ash and particles from automobile and diesel exhaust contain many of these compounds. PAHs and heavy metals are predominantly found in very small particles, which is of concern because some PAHs, such as benzo(a)pyrene, are known carcinogens. Chronic exposure to these particles causes cancers in laboratory animals.
As of 1994, there were 31 million people in the United States in areas that do not meet EPA's current standard for PM-10. However, because PM-10 standards may not be a reliable indicator of the problem presented by fine particles (< 2.5 microns), the 31 million number may be much lower than the real number of people affected by fine particles.
Ecological Effects: Particulate matter causes damage and soiling to materials, and is a major cause of visibility impairment in many parts of the U.S. The same fine particles linked to serious health effects also affects our ability to see by scattering and/or absorbing light. Certain particles, such as sulfates and nitrates, grow in size as humidity increases, making them more effective as impairing visibility.
Visibility conditions vary across the country. Much of the rural eastern U.S. has poorer visibility than rural western sites due to higher levels of particulates from both anthropogenic and natural sources, as well as higher average humidity.
Natural visual ranges in the eastern U.S. is about 90 miles, but current conditions range only from 14-24 miles. In the western U.S., natural visual range is about 140 miles; current conditions range from 33-90 miles.
The CAS established special protection for visibility in certain national parks and wilderness areas. In response, EPA is developing a "regional haze" program intended to ensure continued progress toward the national visibility goal of "no man-made impairment."
Particulate matter can damage vegetation both directly and indirectly. When exposed to particulates, plants may suffer increased disease, leaf cells may be damaged, yield and growth rates may be reduced and plants may even die.
Dust on the leaves of crops, trees and shrubs inhibits photosynthesis and plant growth. Particles carrying heavy metals can contaminate soil and vegetation in urban areas, along highways and near smelters. Once in the soil, heavy metals can accumulate to phytotoxic levels in vegetation and suppress growth. In addition, particulate matter can scatter sunlight and cause a reduction in solar radiation, thereby affecting crop productivity.
One of the most visible effects of particulate matter is the soiling or staining of buildings and textiles. Particulates can also cause chemical deterioration of paint, resulting in corrosion of metal objects.