Air Pollution and Control The Breath of Air TOPIC
Contents Chemistry & Composition (atmosphere) Atmosphere Layers Concept of Air Pollution Air Pollutants & Sources 4 1 2 3 Part I
Contents Greenhouse Effect & Global Warming Effects of Air Pollutants Methods of Air Pollution Control 5 6 7 Part II
Air Pollution… Comes From Many Sources Smog hanging over cities is the most familiar and obvious form of air pollution. But there are different kinds of pollution — some visible, some invisible —that contribute to global warming. Generally any substance that people introduce into the atmosphere that has damaging effects on living things and the environment is considered air pollution.
Chemistry & Composition Atmosphere Atmospheric Composition Atmospheric Chemistry Branch of atmospheric science Multidisciplinary field of research Chemistry of the Earth’s atmosphere & that of the other planets is studied. Draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology & volcanology and other disciplines. Minor constituents: <ul><li>Nitrogen, N 2 - 78.084% </li></ul><ul><li>Oxygen, O 2 – 20.946% </li></ul><ul><li>Argon – 0.934% </li></ul>Note: The mean mol. mass of air is 28.97 g/mol. <ul><li>seeks to understand the causes of acid rain, photochemical smog & global warming. </li></ul><ul><li>CO 2 , Ne, He, CH 4 , Kr, </li></ul><ul><li>H 2 , H 2 O (g) </li></ul>It is of importance because of the interactions between the atmosphere and living organisms .
Atmosphere Layers Exosphere Thermosphere up to 85 km up to 51 km 7 – 17 km Earth's atmosphere can be divided into five main layers . These layers are mainly determined by whether temperature increases or decreases with altitude . 10 4 km up to 693 km Mesosphere Stratosphere Troposphere
Atmosphere Layers Other Layers <ul><li>part of the troposphere, near the earth’s surface affected through turbulent diffusion. </li></ul><ul><li>forms the inner edge of the magnetosphere, ionized by solar radiation. </li></ul>Ozone Layer Ionosphere Homo/hetero-sphere Planetary boundary <ul><li>defined by whether the atmospheric gases are well-mixed. </li></ul><ul><li>90% ozone is contained in the stratosphere (15 -35 km) </li></ul>
Concept of Air Pollution Air pollution and weather are linked in two ways. One concerns the influence that weather conditions have on the dilution and dispersal of air pollutants . The second connection is the reverse and deals with the effect that air pollution has on weather and climate. Air is never perfectly clean. Volcanic ash , salt particles, pollen and spores, smoke, and windblown dust are all examples of “natural air pollution.” One of the most tragic air-pollution episodes occurred in London in December 1952 , when more than 4000 people died.
Concept of Air Pollution <ul><li>Photochemical smog , a noxious mixture of gases and particles, is produced when strong sunlight triggers photochemical reactions in the atmosphere. </li></ul><ul><li>Ozone is the major component of photochemical smog. </li></ul><ul><li>primary pollutants , which are emitted directly from identifiable sources </li></ul><ul><li>secondary pollutants , which are produced in the atmosphere when certain chemical reactions take place among primary pollutants </li></ul>Air Pollutants <ul><li>airborne particles and gases that occur in concentrations that endanger the health and well-being of organisms or disrupt the orderly functioning of the environment. </li></ul>Pollutants 2 categories Smog
Concept of Air Pollution Economic activity , population growth , meteorological conditions , & regulatory efforts to control emissions all influence the trends in air pollution. The Clean Air Act of 1970 mandated the setting of standards for four of the primary pollutants— p articulates, s ulfur dioxide, c arbon monoxide, & n itrogen oxides—as well as the secondary pollutant o zone. The most obvious factor influencing air pollution is the quantity of contaminants emitted into the atmosphere . Two of the most important atmospheric conditions affecting the dispersion of pollutants are (1) the strength of the wind and (2) the stability of the air.
Concept of Air Pollution When an inversion exists and winds are light, diffusion is inhibited and high pollution concentrations are to be expected in areas where pollution sources exist. the greater the mixing depth, the better the air quality . Inversions aloft are associated with sinking air that characterizes centers of high air pressure. <ul><li>Mixing depth – a vertical distance between Earth’s surface and the height to which convectional movements extend; Temperature inversions in w/c the atmosphere is very stable and the mixing depth is restricted. </li></ul>Atmospheric stability
Concept of Air Pollution Acid Precipitation <ul><li>formed when sulfur & nitrogen oxides produced as by-products of combustion and industrial activity are converted into acids during complex atmospheric reactions . </li></ul>producing water that is toxic to fish, acid precipitation has also detrimentally altered complex ecosystems. the damaging effects of acid precipitation on the environment include the lowering of pH in thousands of lakes . Acid Rain Snow
Air Pollutants & Sources Major Air Pollutants Text in here produced by burning of fossil fuels (e.g. fuel oil and coil). A large proportion is produced by power stations and metal smelters which burn sulphur-containing coal, and also by the manufacturing industries which burn fuel oil. Carbon Monoxide produced by the incomplete burning of carbon-containing fuels, such as petrol, coal and wood. Particulates produced by refuse incineration, factories, diesel vehicles, construction sites, and coal/charcoal burners. Particulates are solid or liquid particles which are so small that they remain suspended in the air for a long period of time. Ozone produced by the reaction of oxygen gas with free atoms of oxygen which are formed from the reactions between nitrogen oxides and hydrocarbons in sunlight. produced by petrol- or diesel-burning engines and coal/oil furnaces. Nitrogen oxides Hydrocarbons Sulphur dioxide formed from the evaporation of materials such as petrol, diesel and solvents when exposed to air .
Effects of Air Pollutants Interferes with photosynthesis , carbohydrate production Cancer , asthma, birth defects , eye & respiratory system irritation, and genetic mutation . contribute to sick building syndrome indoors Acid rain : soil, buildings & materials, forest & aquatic life. prolonged exposure to high CO concentrations , unconsciousness, convulsions and death would occur; severe effects on the baby of a pregnant woman. It is important to remember that air pollutants are transboundary , i.e. they know no borders and travel easily from their sources towards other locations spreading pollution throughout the world.
Methods of Air Pollution Control NOx Control Mechanical Collectors (dust cyclone) VOC abatement Electrostatic Precipitators Acid Gas/SO 2 control Baghouses Mercury Control Scrubbers Devices Control Pollution The following items are commonly used as pollution control devices by industry or transportation devices . They can either destroy contaminants or remove them from an exhaust stream before it is emitted into the atmosphere.
Methods of Air Pollution Control (Some things you can do for CLEAN air) Limit Your Family Size Eliminate Toxic Chemical Use at Home Conserve Energy Reduce Waste
Methods of Air Pollution Control (Some things you can do for CLEAN air) No Burn Barrels Cut Back/ Eliminate Lawn Mowing Modify Your Transportation Plant leafy trees and shrubs No Burn Barrels No Burn Barrels No Burn Barrels No Burn Barrels No Burn Barrels Cut Back/ Eliminate Lawn Mowing Cut Back/ Eliminate Lawn Mowing Cut Back/ Eliminate Lawn Mowing Modify Your Transportation Modify Your Transportation Modify Your Transportation Plant leafy trees and shrubs Plant leafy trees and shrubs Plant leafy trees and shrubs Plant leafy trees and shrubs
Thank You! The roots of education are bitter, but the fruit is sweet . Aristotle