Air pollution


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Air pollution

  1. 1. Power point presentation about some aspect related to environmental problems:
  2. 2. What is air pollution? -Air supplies us with oxygen which is essential for our bodies to live. -There are several main types of pollution. These include smog, acid rains, the greenhouse effect, and "hole" in the ozone layer. -One type of air pollution is the release of particles into the air. -Another type of pollution is the release of noxious gases. -. Pollution also needs to be considered inside our homes, offices, and schools.
  3. 3. • Smog-Smog is a type oflarge-scale outdoorpollution. It iscaused by chemicalreactions betweenpollutants derivedfrom differentsources. -Cities are oftencenters of thesetypes of activities.
  4. 4. •Acid rains-It’s caused when apollutant combineswith droplets ofwater in the air.-The effects of acidrain on theenvironment can bevery serious.
  5. 5. •Greenhouse effect-It generally comes from the build up of carbon dioxide gas inthe atmosphere. Carbon dioxide is produced when fuels areburned.-In this type of pollution sun rays go into the atmosphere andthey are trapped by greenhouse-gasses. So the temperature onthe earth raise.
  6. 6. • Hole in the ozone layer -Its another result of pollution. Chemicals released by our activities affect the stratosphere. -Releases of CFC from heating, aerosol cans, refrigerator equipment removes some of the ozone, causing "holes”.
  7. 7. -Some individuals are much more sensitive to pollutants than are others. -Air pollution can affect our health in many ways with both short-term and long-term
  8. 8. -Air pollution preventionefforts of companieshave generally focusedon wastereduction, reuse andrecycling.-So to solve theseproblems and to get overthem we can change ourlifestyles.-If we do these simplethings we could have a
  9. 9. Schematic drawing, causes and effects of air pollution:(1) greenhouse effect,(2) particulate contamination,(3) increased UV radiation,(4) acid rain,(5) increased ground level ozone concentration,(6) increased levels of nitrogen oxides.A substance in the air that can cause harm to humans and the environment is known asan air pollutant. Pollutants can be in the form of solid particles, liquid droplets, orgases. In addition, they may be natural or man-made.Pollutants can be classified as primary or secondary. Usually, primary pollutants aredirectly emitted from a process, such as ash from a volcanic eruption, the carbonmonoxide gas from a motor vehicle exhaust or sulfur dioxide released from factories.Secondary pollutants are not emitted directly. Rather, they form in the air when primarypollutants react or interact. An important example of a secondary pollutant is groundlevel ozone — one of the many secondary pollutants that make up photochemicalsmog. Some pollutants may be both primary and secondary: that is, they are bothemitted directly and formed from other primary pollutants.
  10. 10. Major primary pollutants produced by human activity include:•Sulfur oxides (SOx) - especially sulfur dioxide, a chemical compound with theformula SO2. SO2 is produced by volcanoes and in various industrial processes.Since coal and petroleum often contain sulfur compounds, their combustiongenerates sulfur dioxide. Further oxidation of SO2, usually in the presence of acatalyst such as NO2, forms H2SO4, and thus acid rain. This is one of the causesfor concern over the environmental impact of the use of these fuels as powersources.•Nitrogen oxides (NOx) - especially nitrogen dioxide are emitted from hightemperature combustion, and are also produced naturally during thunderstormsby electrical discharge. Can be seen as the brown haze dome above or plumedownwind of cities. Nitrogen dioxide is the chemical compound with theformula NO2. It is one of the several nitrogen oxides. This reddish-brown toxicgas has a characteristic sharp, biting odor. NO2 is one of the most prominent airpollutants.•Carbon monoxide - is a colorless, odorless, non-irritating but very poisonousgas. It is a product by incomplete combustion of fuel such as natural gas, coalor wood. Vehicular exhaust is a major source of carbon monoxide.•Carbon dioxide (CO2) - a colorless, odorless, non-toxic greenhouse gas alsoassociated with ocean acidification, emitted from sources such as combustion,cement production, and respiration. It is otherwise recycled in the atmospherein the carbon cycle.
  11. 11. •Volatile organic compounds - VOCs are an important outdoor air pollutant. Inthis field they are often divided into the separate categories of methane (CH4)and non-methane (NMVOCs). Methane is an extremely efficient greenhousegas which contributes to enhanced global warming. Other hydrocarbon VOCsare also significant greenhouse gases via their role in creating ozone and inprolonging the life of methane in the atmosphere, although the effect variesdepending on local air quality. Within the NMVOCs, the aromatic compoundsbenzene, toluene and xylene are suspected carcinogens and may lead toleukemia through prolonged exposure. 1,3-butadiene is another dangerouscompound which is often associated with industrial uses.•Particulate matter - Particulates, alternatively referred to as particulate matter(PM) or fine particles, are tiny particles of solid or liquid suspended in a gas. Incontrast, aerosol refers to particles and the gas together. Sources of particulatematter can be man made or natural. Some particulates occur naturally,originating from volcanoes, dust storms, forest and grassland fires, livingvegetation, and sea spray. Human activities, such as the burning of fossil fuelsin vehicles, power plants and various industrial processes also generatesignificant amounts of aerosols. Averaged over the globe, anthropogenicaerosols—those made by human activities—currently account for about 10percent of the total amount of aerosols in our atmosphere. Increased levels offine particles in the air are linked to health hazards such as heart disease, alteredlung function and lung cancer.
  12. 12. •Toxic metals, such as lead, cadmium and copper.•Chlorofluorocarbons (CFCs) - harmful to the ozone layer emitted fromproducts currently banned from use.•Ammonia (NH3) - emitted from agricultural processes. Ammonia is acompound with the formula NH3. It is normally encountered as a gas with acharacteristic pungent odor. Ammonia contributes significantly to thenutritional needs of terrestrial organisms by serving as a precursor tofoodstuffs and fertilizers. Ammonia, either directly or indirectly, is also abuilding block for the synthesis of many pharmaceuticals. Although in wideuse, ammonia is both caustic and hazardous.•Odors — such as from garbage, sewage, and industrial processes•Radioactive pollutants - produced by nuclear explosions, nuclear events, warexplosives, and natural processes such as the radioactive decay of radon.
  13. 13. Secondary pollutants include:•Particulate matter formed from gaseous primary pollutants andcompounds in photochemical smog. Smog is a kind of air pollution;the word "smog" is a portmanteau of smoke and fog. Classic smogresults from large amounts of coal burning in an area caused by amixture of smoke and sulfur dioxide. Modern smog does not usuallycome from coal but from vehicular and industrial emissions that areacted on in the atmosphere by ultraviolet light from the sun to formsecondary pollutants that also combine with the primary emissions toform photochemical smog.•Ground level ozone (O3) formed from NOx and VOCs. Ozone (O3) isa key constituent of the troposphere. It is also an importantconstituent of certain regions of the stratosphere commonly known asthe Ozone layer. Photochemical and chemical reactions involving itdrive many of the chemical processes that occur in the atmosphere byday and by night. At abnormally high concentrations brought about byhuman activities (largely the combustion of fossil fuel), it is apollutant, and a constituent of smog.•Peroxyacetyl nitrate (PAN) - similarly formed from NOx and VOCs.
  14. 14. Minor air pollutants include:•A large number of minor hazardous air pollutants. Someof these are regulated in USA under the Clean Air Act andin Europe under the Air Framework Directive.•A variety of persistent organic pollutants, which canattach to particulate matter.Persistent organic pollutants (POPs) are organiccompounds that are resistant to environmental degradationthrough chemical, biological, and photolytic processes.Because of this, they have been observed to persist in theenvironment, to be capable of long-range transport,bioaccumulation in human and animal tissue,biomagnified in food chains, and to have potentialsignificant impacts on human health and the environment
  15. 15. • Air pollution is also emerging as a risk factor for stroke, particularly in developing countries where pollutant levels are highest. A recent study also found an association in women between air pollution and ischemia, but not hemorrhagic stroke. Air pollution has also been associated with increased incidence and mortality from coronary artery disease.
  16. 16. • A study from around the years of 1999 to 2000, by the University of Washington, showed that patients near and around particulate matter air pollution had an increased risk of pulmonary exacerbations and decrease in lung function. Patients were examined before the study for amounts of specific pollutants like Pseudomonas aeruginosa or Burkholderia cenocepacia as well as their socioeconomic standing. Participants involved in the study were located in the United States in close proximity to an Environmental Protection Agency. During the time of the study 117 deaths were associated with air pollution. Many patients in the study lived in or near large metropolitan areas in order to be close to medical help. These same patients had higher level of pollutants found in their system because of more emissions in larger cities. As cystic fibrosis patients already suffer from decreased lung function, everyday pollutants such as smoke, emissions from automobiles, tobacco smoke and improper use of indoor heating devices could further compromise lung function.
  17. 17. Chronic obstructive pulmonary disease (COPD) includes diseases such aschronic bronchitis and emphysema.Researches have demonstrated increased risk of developing asthma and COPDfrom increased exposure to traffic-related air pollution. Additionally, airpollution has been associated with increased hospitalizations and mortality fromasthma and COPD.A study conducted in 1960-1961 in the wake of the Great Smog of 1952compared 293 London residents with 477 residents of Gloucester,Peterborough, and Norwich, three towns with low reported death rates fromchronic bronchitis. All subjects were male postal truck drivers aged 40 to 59.Compared to the subjects from the outlying towns, the London subjectsexhibited more severe respiratory symptoms (including cough, phlegm, anddyspnea), reduced lung function (FEV1 and peak flow rate), and increasedsputum production and purulence. The differences were more pronounced forsubjects aged 50 to 59.
  18. 18. The study controlled for age andsmoking habits, so concludedthat air pollution was the mostlikely cause of the observeddifferences.It is believed that much likecystic fibrosis, by living in amore urban environment serioushealth hazards become moreapparent. Studies have shownthat in urban areas patients suffermucus hyper secretion, lowerlevels of lung function, and moreself diagnosis of chronicbronchitis and emphysema.
  19. 19. The basic technology for analyzing air pollution is through the use of a varietyof mathematical models for predicting the transport ofair pollutants in the lower atmosphere.The principal methodologies are:•Point source dispersion, used for industrial sources.•Line source dispersion, used for airport and•roadway air dispersion modeling•Area source dispersion, used for forest fires or• dust storms•Photochemical models, used to analyze reactive• pollutants that form smogVisualization of a buoyant Gaussian air pollution dispersion plume as used in many atmospheric dispersion modelsThe point source problem is the best understood, since it involves simpler mathematics and has been studied for along period of time, dating back to about the year 1900. It uses a Gaussiandispersion model for buoyant pollution plumes to forecast the air pollutionisopleths, with consideration given to wind velocity, stack height, emission rateand stability class (a measure of atmospheric turbulence). This model has beenextensively validated and calibrated with experimental data for all sorts ofatmospheric conditions
  20. 20. The roadway air dispersion model was developed starting in the late 1950s andearly 1960s in response to requirements of the National Environmental PolicyAct and the U.S. Department of Transportation (then known as the FederalHighway Administration) to understand impacts of proposed new highwaysupon air quality, especially in urban areas. Several research groups were activein this model development, among which were: the Environmental Researchand Technology (ERT) group in Lexington, Massachusetts, the ESL Inc. groupin Sunnyvale, California and the California Air Resources Board group inSacramento, California. The research of the ESL group received a boost with acontract award from the United States Environmental Protection Agency tovalidate a line source model using sulfur hexafluoride as a tracer gas. Thisprogram was successful in validating the line source model developed by ESLinc. Some of the earliest uses of the model were in court cases involvinghighway air pollution, the Arlington, Virginia portion of Interstate 66 and theNew Jersey Turnpike widening project through East Brunswick, New Jersey.Area source models were developed in 1971 through 1974 by the ERT and ESLgroups, but addressed a smaller fraction of total air pollution emissions, so thattheir use and need was not as widespread as the line source model, whichenjoyed hundreds of different applications as early as the 1970s. Similarlyphotochemical models were developed primarily in the 1960s and 1970s, buttheir use was more specialized and for regional needs, such as understandingsmog formation in Los Angeles, California.