Air Pollution

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  1. 1 Topic: Air Pollution, pollutants, sources, effect, greenhouse gases, global warming and climate change. Air pollution: Air pollution is the introduction of…
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  • 1. 1 Topic: Air Pollution, pollutants, sources, effect, greenhouse gases, global warming and climate change. Air pollution: Air pollution is the introduction of particulates, biological molecules, or other harmful gases into Earth's atmosphere, causing disease, death to humans, damage to other living organisms such as food crops, or the natural or built environment. Types of Air Pollution Sources: There are four main types of air pollution sources:  mobile sources – such as cars, buses, planes, trucks, and trains  stationary sources – such as power plants, oil refineries, industrial facilities, and factories  area sources – such as agricultural areas, cities, and wood burning fireplaces  natural sources – such as wind-blown dust, wildfires, and volcanoes Mobile sources account for more than half of all the air pollution in the United States and the primary mobile source of air pollution is the automobile, according to the Environmental Protection Agency. Stationary sources, like power plants, emit large amounts of pollution from a single location, these are also known as point sources of pollution. Area sources are made up of lots of smaller pollution sources that aren't a big deal by themselves but when considered as a group can be. Natural sources can sometimes be significant but do not usually create ongoing air pollution problems like the other source types can. Anthropogenic Sources of Air Pollution: 1. Burning of Fossil Fuels: Sulfur dioxide emitted from the combustion of fossil fuels like coal, petroleum and other factory combustibles is one the major cause of air pollution. Pollution emitting from vehicles including trucks, jeeps, cars, trains, airplanes cause immense amount of pollution. We rely on them to fulfill our daily basic needs of transportation. But, there overuse is killing our environment as dangerous gases are polluting the environment. Carbon Monoxide caused by improper or incomplete combustion and generally emitted from vehicles is another major pollutant along with Nitrogen Oxides that is produced from both natural and manmade processes.
  • 2. 2 2. Agricultural activities: Ammonia is a very common by product from agriculture related activities and is one of the most hazardous gases in the atmosphere. Use of insecticides, pesticides and fertilizers in agricultural activities has grown quite a lot. They emit harmful chemicals into the air and can also cause water pollution. 3. Exhaust from factories and industries: Manufacturing industries release large amount of carbon monoxide, hydrocarbons, organic compounds, and chemicals into the air thereby depleting the quality of air. Manufacturing industries can be found at every corner of the earth and there is no area that has not been affected by it. Petroleum refineries also release hydrocarbons and various other chemicals that pollute the air and also cause land pollution. 4. Mining operations: Mining is a process wherein minerals below the earth are extracted using large equipments. During the process dust and chemicals are released in the air causing massive air pollution. This is one of the reasons which are responsible for the deteriorating health conditions of workers and nearby residents. 5. Indoor air pollution: Household cleaning products, painting supplies emit toxic chemicals in the air and cause air pollution. Have we ever noticed that once we paint walls of war house, it creates some sort of smell which makes it literally impossible for us to breathe. Suspended particulate matter popular by its acronym SPM, is another cause of pollution. Referring to the particles afloat in the air, SPM is usually caused by dust, combustion etc. Natural Sources of Air Pollution: The natural sources of air pollution emissions include:  Volcanoes: Volcanic activity produces smoke, ash, carbon dioxide, sulfur dioxide and other air pollutants.  Geysers: The air pollutants emitted by geysers include hydrogen sulfide, arsenic and other heavy metals.  Digestive gases: Methane and other gases generated by the digestion of food and emitted by animals such as cattle.  Oceans, Rivers and Estuaries: These are sources of methane emissions thought to be caused by the digestive systems of marine life, methanogenesis in sediments and drainage areas along coastal regions, and possibly seepage from methane hydrates on the ocean floors.  Dust: Windblown dust from areas with little or no vegetation such as desert areas.  Sea salt: Wind-blown sea water which evaporates in the atmosphere and releases sodium chloride and other particulates into the atmosphere.  Radioactive decay: Radon gas is released into the atmosphere by radioactive decay occurring in the Earth's crust.  Forest fires: Forest fires created by lightning, or other natural causes, result in the formation and release of smoke, ash, dust, carbon dioxide, nitrogen oxides and other air pollutants.
  • 3. 3  Plants and trees: Biogenic sources such as pine trees and certain other plants and trees which release volatile organic compounds (VOC). About 80% of the overall emissions of VOC are from biogenic sources.  Wetlands: Microbial action in wetlands result in significant amounts of methane being formed and released to the atmosphere. In fact, wetlands are the largest natural source of methane emissions.  Termites: Termites are the second largest natural source of methane emissions. The methane is produced by their normal digestive process.  Lightning: Lightning converts atmospheric nitrogen to nitrogen oxides.  Soil out gassing: Another biogenic source wherein microbial action in soils result in the formation and release of significant amounts of nitrogen oxides. Effects of Air pollution 1. Respiratory and heart problems: The effects of Air pollution are alarming. They are known to create several respiratory and heart conditions along with Cancer, among other threats to the body. Several millions are known to have died due to direct or indirect effects of Air pollution. Children in areas exposed to air pollutants are said to commonly suffer from pneumonia and asthma. 2. Global warming: Another direct effect is the immediate alterations that the world is witnessing due to Global warming. With increased temperatures world wide, increase in sea levels and melting of ice from colder regions and icebergs, displacement and loss of habitat have already signaled an impending disaster if actions for preservation and normalization aren’t undertaken soon. 3. Acid Rain: Harmful gases like nitrogen oxides and sulfur oxides are released into the atmosphere during the burning of fossil fuels. When it rains, the water droplets combines with these air pollutants, becomes acidic and then falls on the ground in the form of acid rain. Acid rain can cause great damage to human, animals and crops. 4. Eutrophication: Eutrophication is a condition where high amount of nitrogen present in some pollutants gets developed on sea’s surface and turns itself into algae and adversely affect fish, plants and animal species. The green colored algae that are present on lakes and ponds is due to presence of this chemical only. 5. Effect on Wildlife: Just like humans, animals also face some devastating effects of air pollution. Toxic chemicals present in the air can force wildlife species to move to new place and change their habitat. The toxic pollutants deposit over the surface of the water and can also affect sea animals. 6. Depletion of Ozone layer: Ozone exists in earth’s stratosphere and is responsible for protecting humans from harmful ultraviolet (UV) rays. Earth’s ozone layer is depleting due to the presence of chlorofluorocarbons, hydro chlorofluorocarbons in the atmosphere. As ozone layer will go thin, it will emit harmful rays back on earth and can cause skin and eye related problems. UV rays also have the capability to affect crops.
  • 4. 4 Effect on Human Health: Ozone (O3) Nature and Sources of the Pollutant: Ground-level ozone (the primary constituent of smog) is the most complex, difficult to control, and pervasive of the six principal pollutants. Unlike other pollutants, ozone is not emitted directly into the air by specific sources. Ozone is created by sunlight acting on nitrogen oxides (NOx) and volatile organic compound (VOC) emissions in the air. There are literally thousands of sources of these gases. Some of the more common sources include gasoline vapors, chemical solvents, combustion products of various fuels, and consumer products. They can originate from large industrial facilities, gas stations, and small businesses such as bakeries and dry cleaners. Often these "precursor" gases are emitted in one area, but the actual chemical reactions, stimulated by sunlight and temperature, take place in another. Combined emissions from motor vehicles and stationary sources can be carried hundreds of miles from their origins, forming high ozone concentrations over very large regions. Approximately 50 million people lived in counties with air quality levels above EPA's health- based national air quality standard in 1994. The highest levels of ozone were recorded in Los Angeles. High levels also persist in other heavily populated areas like the Texas Gulf Coast and much of the Northeast. Health and Other Effects: Scientific evidence indicates that ground-level ozone not only affects people with impaired respiratory systems (such as asthmatics), but healthy adults and children as well. Exposure to ozone for 6 to 7 hours, even at relatively low concentrations, significantly reduces lung function and induces respiratory inflammation in normal, healthy people during periods of moderate exercise. It can be accompanied by symptoms such as chest pain, coughing, nausea, and pulmonary congestion. Recent studies provide evidence of an association between elevated ozone levels and increases in hospital admissions for respiratory problems in several U.S. cities. Results from animal studies indicate that repeated exposure to high levels of ozone for several months or more can produce permanent structural damage in the lungs. EPA's health- based national air quality standard for ozone is 0.12 ppm (measured at the highest hour during the day). Ozone is also responsible for several billion dollars of agricultural crop yield loss in the U.S. each year. Nitrogen Dioxide (NO2) Nature and Sources of the Pollutant: Nitrogen dioxide belongs to a family of highly reactive gases called nitrogen oxides (NOx). These gases form when fuel is burned at high temperatures, and come principally from motor vehicle exhaust and stationary sources such as electric utilities and industrial boilers. A suffocating, brownish gas, nitrogen dioxide is a strong oxidizing agent that reacts in the air to form corrosive nitric acid, as well as toxic organic nitrates. It also plays a major role in the atmospheric reactions that produce ground-level ozone (or smog). Health and Other Effects: Nitrogen dioxide can irritate the lungs and lower resistance to
  • 5. 5 respiratory infections such as influenza. The effects of short-term exposure are still unclear, but continued or frequent exposure to concentrations that are typically much higher than those normally found in the ambient air may cause increased incidence of acute respiratory illness in children. EPA's health-based national air quality standard for NO2 is 0.053 ppm (measured as an annual average). Nitrogen oxides are important in forming ozone and may affect both terrestrial and aquatic ecosystems. Nitrogen oxides in the air are a potentially significant contributor to a number of environmental effects such as acid rain and eutrophication in coastal waters like the Chesapeake Bay. Eutrophication occurs when a body of water suffers an increase in nutrients that reduce the amount of oxygen in the water, producing an environment that is destructive to fish and other animal life. Particulate Matter (PM-10 and PM-2.5) Nature and Sources of the Pollutants: Particulate matter is the term for solid or liquid particles found in the air. Some particles are large or dark enough to be seen as soot or smoke. Others are so small they can be detected only with an electron microscope. Because particles originate from a variety of mobile and stationary sources (diesel trucks, wood stoves, power plants, etc.), their chemical and physical compositions vary widely. Health and Other Effects: In 1987, EPA replaced the earlier Total Suspended Particulate (TSP) air quality standard with a PM-10 standard. The standard focuses on smaller particles that are likely responsible for adverse health effects because of their ability to reach the lower regions of the respiratory tract. The PM-10 standard includes particles with a diameter of 10 micrometers or less (0.0004 inches or one-seventh the width of a human hair). EPA's health-based national air quality standard for PM-10 is 50 micrograms per cubic meter (measured as an annual average) and 150 micrograms per cubic meter (measured as a daily average). In 1997, EPA promulgated a PM-2.5 standard which includes particles with a diameter of 2.5 microns or less. These smaller particles have the best chance of reaching the lower respiratory tract. The health-based national ambient air quality standard for PM-2.5 is 15 micrograms per cubic meter (measured as an annual average) and 65 micrograms per cubic meter (measured as a daily average). Major concerns for human health from exposure to particulate matter are: effects on breathing and respiratory systems, damage to lung tissue, cancer, and premature death. The elderly, children, and people with chronic lung disease, influenza, or asthma, tend to be especially sensitive to the effects of particulate matter. Acidic particulate matter can also damage manmade materials and is a major cause of reduced visibility in many parts of the U.S. Sulfur Dioxide (SO2) Nature and Sources of the Pollutant: Sulfur dioxide belongs to the family of sulfur oxide gases (SOx). These gases are formed when fuel containing sulfur (mainly coal and oil) is burned, and during metal smelting and other industrial processes.
  • 6. 6 Health and Other Effects: The major health concerns associated with exposure to high concentrations of SO2 include effects on breathing, respiratory illness, alterations in pulmonary defenses, and aggravation of existing cardiovascular disease. Major subgroups of the population that are most sensitive to SO2 include asthmatics and individuals with cardiovascular disease or chronic lung disease (such as bronchitis or emphysema) as well as children and the elderly. EPA's health-based national air quality standard for SO2 is 0.03 ppm (measured on an annual average) and 0.14 ppm (measured over 24 hours). Emissions of SO2 also can damage the foliage of trees and agricultural crops. EPA has a secondary SO2 national ambient air quality standard of 0.50 ppm (measured over 3 hours) designed to prevent this type of environmental deterioration. Together, SO2 and NOX are the major precursors to acid rain, which is associated with the acidification of lakes and streams, accelerated corrosion of buildings and monuments, and reduced visibility. Lead (Pb) Nature and Sources of the Pollutant: Smelters and battery plants are the major sources of the pollutant "lead" in the air. The highest concentrations of lead are found in the vicinity of nonferrous smelters and other stationary sources of lead emissions. Health Effects: Exposure to lead mainly occurs through inhalation of air and ingestion of lead in food, paint, water, soil, or dust. Lead accumulates in the body in blood, bone, and soft tissue. Because it is not readily excreted, lead can also affect the kidneys, liver, nervous system, and other organs. Excessive exposure to lead may cause anemia, kidney disease, reproductive disorders, and neurological impairments such as seizures, mental retardation, and/or behavioral disorders. Even at low doses, lead exposure is associated with changes in fundamental enzymatic, energy transfer, and other processes in the body. Fetuses and children are especially susceptible to low doses of lead, often suffering central nervous system damage or slowed growth. Recent studies show that lead may be a factor in high blood pressure and subsequent heart disease in middle-aged white males. Lead may also contribute to osteoporosis in postmenopausal women. EPA's health-based national air quality standard for lead is 1.5 micrograms per cubic meter [measured as a quarterly average]. Carbon Monoxide (CO) Nature and Sources of the Pollutant: Carbon monoxide is a colorless odorless poisonous gas formed when carbon in fuels is not burned completely. It is a byproduct of motor vehicle exhaust, which contributes more than two-thirds of all CO emissions nationwide. In cities, automobile exhaust can cause as much as 95 percent of all CO emissions. These emissions can result in high concentrations of CO, particularly in local areas with heavy traffic congestion. Other sources of CO emissions include industrial processes and fuel combustion in sources such as boilers and incinerators. Despite an overall downward trend in concentrations and emissions
  • 7. 7 of CO, some metropolitan areas still experience high levels of CO. Health and Other Effects: Carbon monoxide enters the bloodstream and reduces oxygen delivery to the body's organs and tissues. The health threat from CO is most serious for those who suffer from cardiovascular disease. Healthy individuals are also affected, but only at higher levels of exposure. Exposure to elevated CO levels is associated with visual impairment, reduced work capacity, and reduced manual dexterity, poor learning ability, and difficulty in performing complex tasks. EPA's health based national air quality standard for CO is 9 parts per million (ppm) [measured over 8 hours]. Common Air Pollutants: Figure: Common Air Pollutants Carbon Monoxide (CO)  Fuel combustion from vehicles and engines.  Reduces the amount of oxygen reaching the body’s organs and tissues; aggravates heart disease, resulting in chest pain and other symptoms. Ground-level Ozone (O3)  Secondary pollutant formed by chemical reaction of volatile organic compounds (VOCs)
  • 8. 8 and NOx in the presence of sunlight.  Decreases lung function and causes respiratory symptoms, such as coughing and shortness of breath, and also makes asthma and other lung diseases get worse. More on Ground Level Ozone Here Lead (Pb)  Smelters (metal refineries) and other metal industries; combustion of leaded gasoline in piston engine aircraft; waste incinerators (waste burners), and battery manufacturing.  Damages the developing nervous system, resulting in IQ loss and impacts on learning, memory, and behavior in children. Cardiovascular and renal effects in adults and early effects related to anemia. Nitrogen Dioxide (NO2)  Fuel combustion (electric utilities, big industrial boilers, vehicles) and wood burning.  Worsens lung diseases leading to respiratory symptoms, increased susceptibility to respiratory infection. Particulate Matter (PM)  This is formed through chemical reactions, fuel combustion (e.g., burning coal, wood, diesel), industrial processes, farming (plowing, field burning), and unpaved roads or during road constructions.  Short-term exposures can worsen heart or lung diseases and cause respiratory problems. Long-term exposures can cause heart or lung disease and sometimes premature deaths. Sulfur Dioxide (SO2)  SO2 comes from fuel combustion (especially high-sulfur coal); electric utilities and industrial processes as well as natural occurrences like volcanoes.  Aggravates asthma and makes breathing difficult. It also contributes to particle formation with associated health effects. Air pollution prevention, monitoring and solution: Solution efforts on po
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