Chapter 16: Air Quality Issue THE ATMOSPHERE (Fig. 16.1) 1. It contains 78.1% N2, 20.9% O2 and trace amount of H2, Ar, CO2, CH4, H2O(g), etc. 2. It is held together by gravitational force. 3. There are four layers of atmosphere: Troposphere Stratosphere Mesosphere Thermosphere A layer extends to A layer extends from A layer with A layer with above 10 km (~6.2 the top of the decreasing increasing miles) above the troposphere to above temperatures from 50 temperature that Earth. 50 km (~31 miles) and ~80 km (31~50) extends to above 300 contains most of the above the Earth. km (186 miles) above ozone. the Earth surface. It actually varies from The ozone is in a about 8~18 km (5~11 band between 15~30 miles), depending on km (9~19 miles) the position of the above the Earth’s Earth, and the season surface. of the year. Temperature declines Ozone layer absorbs 0 0 by 6 C (or 11 F) for sunlight. The upper every km above the layers of the surface. stratosphere are warmer than the lower layers. It contains most of the water vapor of the atmosphere and is the layer where the weather takes place. 4. The air is not static: a) Air expands and rises when it absorbs heat from the Earth. b) When air’s heat content is radiated into space, the air cols, becomes denser, and flows toward the Earth. c) Air circulates vertically due to heating and cooling, it also moves horizontally over the surface of the Earth because the Earth rotates on its axis. d) The combination of all air movements creates the wind and weather (Fig. 16.2). POLLUTION OF THE ATMOSPHERE 1. Pollution: The description of any addition of matter or energy that degrades environment for humans and other organisms. 2. Causes: Human factors Nonhuman factors Human activities are the major cause of Minor cause of pollution pollution Controllable Uncontrollable Automobile emissions Materials emitted from volcanoes Chemical odors Dust from wind erosion Factory smoke Gases from the decomposition of dead plants and animals a) Air pollution is directly related to the number of people living in an area and the kind of activities in which they are involved. b) The pollutants released into the air are diluted, carried away by the wind, washed from air by rain, or react with O2 in the air to form harmless materials. Thus, the overall negative effect is light.

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c) Industrialized civilization has dense contractions of people that use large quantities of fossil fuels for manufacturing, transportation, and domestic purposes. The activities release large quantities of polluting by-products into our environments. d) We do not get rid of gases or small particles released into atmosphere: they are diluted and moved out of the immediate area. e) In industrialized urban areas, pollutants cannot always be diluted sufficiently before the air reaches another city. fortified Ex. Chicago  Gary, Indiana  Detroit & Cleveland  Southern Canada & New England  Ocean. Ex. Ground level O3 is a by-product of automobile usage, which can severely damage lung tissue. (Note: O3 in upper atmosphere is valuable in protecting the Earth). Ex. Poor air quality has linked to many health problems including deaths: Chronic coughing, bronchial inflammations, allergic reactions, and irritation of the mucous membrane of the eyes and nose all indicate that air pollution must be reduced. CAREGORIES OF AIR POLLUTANTS Primary air pollutants Secondary air pollutants Criteria air pollutants Releasing in the unmodified 1. They are formed by primary 1. A special category of air forms in sufficient quantities air pollutants that interact with pollutants. poses a health risk. one another in the presence of 2. Have established air quality sunlight to form new standards. compounds. 2. They are also formed from reactions with substances that occur naturally in the atmosphere. CO, VOCs, particulate matter, O3 NO2, O3, SO2, PM, CO, Pb SO2, NOx VOCs: volatile organic compounds (hydrocarbons) PM: Particulate matter NOx: oxides of nitrogen Note: 1. CO, Pb, NO2 and SO2 are emitted directly from a variety of sources. 2. O3 is not emitted but formed when NOx and VOCs react in the presence of sunlight. 3. PM can be directly emitted, or it can be formed when NO x and SOx, NH3, organic compounds, and other gases react in the atmosphere (Table 16.1) 4. Some are highly toxic and are known as hazardous air pollutants or air toxics. Carbon Monoxide (CO) (Fig. 16.4) 1. Produces when a matter containing carbon burns in insufficient oxygen. If there is enough oxygen, then CO2 is produced. 2. It binds to hemoglobin in blood better and stronger than oxygen, which reduces the blood’s oxygen carrying capacity. 3. Several hours of exposure to air containing 0.001% CO can cause death. The amount produced in heavy traffic can cause headache, drowsiness, and blurred vision. 4. Cigarette smoking is an important source of CO and the smoker inhales it directly. A smoker in a congested traffic is doubly exposed and may experience severely impaired reaction time compared to a nonsmoking driver. 5. Not a persistent pollutant as it reacts with oxygen readily to form CO2. 6. Catalytic converters reduce the amount of CO released by vehicle engines, and specially formulated fuels, used mostly in winter, can reduce production of CO.

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Ex. It used to add tetra ethyl lead before 1970 and then MTBE (methyl tert-butyl ether) before 1995 to promote octane-rating. The former is banned nation-wide and the later is banned in most of the states. Ethanol is now a choice. Particulate Matter 1. It consists of minute (10 microns and smaller) solid particles and liquid droplets dispersed into -6 the atmosphere. Note: 1 µm = 1 micron = 10 m. 2. Categories PM10 PM2.5 size < 10 µm (Corse particles: > 2.5 µm) < 2.5 µm (Fine particles) type Released directly into air Mostly are secondly pollutants formed in the atmosphere from interaction of primary pollutants example Dust or carbon from construction site, Sulfates and nitrates smoke particles from fire, industrial processes, travel on road, etc. Side effect Reduced visibility, soot, carcinogenic Reduced visibility, soot, (asbestos), can accumulate in lung carcinogenic (asbestos), can and reduce its ability to exchange accumulate in lung and reduce gases its ability to exchange gases Effects of EPA Decreased by 80% between 1970 and Decreased by 7% between Standards 2004 1996 and 2002. Sulfur Dioxide (SO2) 1. It is produced by burning S-containing matter, like fossil fuels (coal and oil). 2. Over 65% of SO2 released into the atmosphere is from power plants, primarily those that burn coal. 3. It has a sharp odor, irritates respiratory tissue, and aggravates asthmatic and other respiratory conditions. 4. It reacts with water, oxygen, and other materials in air to form sulfur-containing acids (H2SO4 and H2SO3) and involved in acid deposition (acid rain). 5. Its combination with smoke and fog was known as smog, which causes severe bronchial irritation, sore throats, and chest pains, causing four thousand people died in a few weeks in London, 1952. 6. In U.S. its release decreased ~51% between 1970 and 2004. Nitrogen Dioxide (NO2) 1. Burning of fossil fuels produces a mixture of nitrogen-containing compounds, known as oxides of nitrogen, mainly are NO and NO2. NO can further react with oxygen to produce NO 2, the secondary pollutant. 2. NO2, reddish brown, highly active, is responsible in production of the mixture of secondary air pollutants known as photochemical smog or haze seen over cities, causing respiratory problems. It is also a component of acid rain (as nitric acid, HNO3). 3. The primary source of nitrogen oxides is the automobile engine, which accounts for ~50% of oxides of nitrogen released. 4. Catalytic converters significantly reduce the amount of NO released from the internal combustion engine: About 75% of NO is converted back to N2 and O2. 5. Increase in number of cars and distance driven, the release of nitrogen oxides only decreases 30% between 1970 and 2004. EPA estimates prior to 2000 suggested that NO x levels were actually increasing. Lead (Pb) 1. It enters the body when human inhale airborne particles or consume lead that was deposited on surfaces and can cause mental retardation and kidney damage.

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2. Primary source of airborne Pb was the additive of gasoline, which was later removed in North America and Europe. Many other countries in the worlds still use leaded gasoline but are moving toward eliminating it. Currently ~80% gasoline sold in the world is unleaded. (Fig. 16.5) 3. Another major source is lead paint. Many older homes have lead paints as lead compounds are colorful. Remodeling, flaking paint or demolition releases lead into atmosphere. 4. Today ~80% of lead emission is from metal smelters and manufacturers of batteries. Volatile Organic Compounds (VOCs) 1. Source: automobiles from fuel or exhaust; refineries and other industries; oil-based paint, charcoal lighter, and other chemicals. Automobiles Refineries and other industries ~45% release ~90% release 2. Components: containing mainly hydrogen and carbon. Often refers to hydrocarbons. 3. Some are toxic and known as hazardous pollutants. 4. They contribute to the production of the secondary air pollutants found in smog. 5. Modifications to reduce its release into the air from automobiles: a) Recycling some gases through the engine so they can burn rather than escape b) Increasing the proportion of oxygen in the fuel–air mixture to obtain more complete burning of the fuel c) Using devices to prevent the escape of gases from the fuel tank and crankcase d) Catalytic converter allows unburned organic compounds in the exhaust gases to be oxidized more completely so that fewer volatile organic compounds leave the tailpipe. 6. Reduction of release from industries: a) Requiring industries to account for their emissions and encouraging the substitution of nonvolatile compounds for volatile organic compounds: Ex. Increase using paints and coatings that do not require organic solvents 7. The emissions have been reduced by 55% between 1970 and 2004. Ground-Level Ozone and Photochemical Smog 1. Ozone is an extremely active molecule: a) It irritates respiratory tissues and causes lung damage. b) It damages plants and reduces agricultural yields. 2. It is a secondary pollutant and is formed as a component of photochemical smog, which is a mixture of pollutants including ozone, aldehydes, and peroxyacetylnitrates that results from the interaction of NO2 and VOCs with sunlight in a warm environment. 3. The most destructive components of photochemical smog area ozone and peroxyacetyl nitrates: a) Both are excellent oxidizing agents, which reactive with many other compounds including those found in living things. b) Ozone destroys chlorophyll in plants and injuries lung tissue in humans and other animals. c) Peroxyacetyl nitrates are eye irritants. 4. Ingredients Required for Photochemical Smog Development: a) NO, NO2 and VOCs, by-products of cars and industrial processes, must be present and sunlight and temperature are important to support the chemical reactions. b) Major steps in the development of photochemical smog: (Fig. 16.7)

sunlight NO2 -------------- NO + O* O* + O2 --------------- O3 O* or O3 + organic molecule --------------- organic free radical NO + free radical ------------- NO2 + other organic molecules

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c) Daily changes in pollutants during photochemical smog incident: (Fig 16.8) d) Smog developed in an area can pose more problems than others due to the climate, traffic, and geographic features: Cities adjacent to mountain ranges or in valleys have greater problems because pollutants are trapped by thermal inversion. e) Thermal inversion: (Fig. 16.9) A layer of warmer air may be above a layer of cooler air at the Earth’s surface is called thermal inversion. Normally the air is warmer at the surface of the Earth and gets cooler at higher altitudes. Smog can be reduced by reducing NOx and VOCs associated with the use of internal combustion engines or by moving population centers away from valleys where thermal inversion occurs. 5. Hazardous air pollutants (HAP): a) Hundreds of other dangerous chemical compounds are purposely or accidentally released to the air that can cause harm to human health or damage the environment. These compounds are collectively known as hazardous air pollutants or air toxics. Ex. Pesticides are toxic materials that are purposely released to kill insects or other pests Ex. Benzene in gasoline escapes when gasoline is put into the tank, and the use of some consumer products such as glue and cleaners releases toxic materials into air. b) The majority of air toxics are released as a result of manufacturing processes. Ex. Perchloroethylene is released from dry cleaning establishments and the toxic materials are released from smelters. The chemical and petroleum industries are the primary sources of hazardous air pollution. CONTROL OF AIT POLLUTION Methods of controlling air pollution depend on the type of pollutant and the willingness or abililty of industries, governments, and individuals to make changes. 1) Motor vehicle emissions: The primary sources of air pollutants from motor vehicles are CO, VOCs, and NOx. The secondary pollutant of motor vehicles is O3. Placing the control on emissions has improved in the air quality in the North America. b) Positive crankcase ventilation value and gas caps with air-pollution control valves reduce VOC loss. Better fuel efficiency and specially blended fuels that produce less CO and unburned organic compounds have improved air quality. Catalytic converters reduced CO, NOx, and VOCs in emission and necessitated the used of unleaded fuel. Added Questions: a) Is that worthy to add ethanol into gasoline? Ethanol reduces fuel efficiency if the industry does not redesign the engine. b) Gasoline engine is not as efficient as diesel engine. Why continue to use gasoline engine in all vehicles? Though diesel engine produces more particulates than gasoline, European countries have more cars equipped with diesel engines than the ones with gasoline engines, which generate finer particulates. The air quality standards in Europe are stricter than in the U.S. Are there any trade-off effects or political interests? 2) Particulate matter emissions: a) It came from various sources: industrial activities involve processes that produce dusts (mining and other earth-moving activities, farming operations, and transfer of grain or coal from one container to another, etc.) b) Improper land use can be a major source of airborne particles: satellites have tracked large amounts of dust and industrial pollution rapidly moving from Asia across the Pacific toward North America. In 2000, large volumes of dust from the Gobi Desert in Mongolia and other Asia deserts and adjacent overgrazed regions traveled in a cloud across the Pacific, reaching as far east as Texas. The sky in Seattle, Vancouver, and other West Coast cities turned a visible milky white from the presence of dust particles. c) Burning of fossil fuels is another major source of particulate matter. Though the devices used to trap the particulates from burning of fossil fuels has effectively reduced the amount of

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particulates, the smaller particles that form from gaseous emissions (SO2, NOx) are still a problem. Diesel engines are a significant source of particulate matter and the gaseous emissions from motor vehicles contribute to the formation of smaller particles in the same way that industrial sources do. d) Individual personal activities: Wood used as primary source of fuel for cooking and heating by many people in the world. In U.S. and Canada, some people use wood-burning fireplace and stoves as a primary source of heat, but other use wood for supplemental heat or for aesthetic purposes. However, the large number of wood-burning stoves and fireplaces can generate a significant air-pollution problem, called brown cloud. Boise, Idaho, Salt Lake City, Utah, and Denver, Colorado impose fines to enforce a ban on wood-burning during severe airpollution episodes. 6. Power plant emissions: a) Sulfur dioxide is produced primary by electric-power generating plants. Thus, there are many ways to control SO2 emission: i) First alternative: switching from high-sulfur coal to low-sulfur coal in power generation reduces 66% of sulfur released to atmosphere. Switching to oil or natural gas or nuclear fuels would reduce SO2 emission even more. However, these are not the long-term solution as lowsulfur coal is in short supply and the nuclear power plants pose a different set of pollution problems. (See chapter 10) ii) Second alternative is to remove the sulfur from the fuel before the fuel is used: Chemical or physical treatment of coal before it is burned can remove ~40% of the sulfur. It is technically possible but increases the cost of electricity to the rate payer. iii) Third alternative: Scrubbing the gases emitted from a smokestack. The technology is available but the control devices are costly to install, maintain, and operate. Governments have required the installation of these devices, but when the industries install them, the cost of construction and operation is passed on to the consumer. (~200 million to install scrubbers.) 7. The Clean Air Act: Initially enacted in 1967 as the Air Quality Act and extensively amended in 1970, 1977, and 1990. a) In U.S., the implementation of the requirements of the Clean Air Act has been the primary means of controlling air pollution. It provides the principal framework for national, state, tribal, and local efforts to protect air quality. b) EPA’s responsibilities under Clean Air Act: 1) Conducting periodic reviews for the six principal pollutants that are considered harmful to public health and the environment. 2) Ensuring the air quality standards are met through national standards and strategies to control air pollutant emissions from vehicles, factories, and other sources. 3) Reducing emissions of SO2 and NOx that cause acid rain. 4) Reducing air pollutants such as PM (particulate matter), SOx, and NOx, which can reduce visibility across large regional areas, including the nation’s most treasured parks and wilderness areas. 5) Ensuring that sources of toxic air pollutants that may cause cancer and other adverse human health and environmental effects are well controlled and the risks to public health and the environment are substantially reduced. 6) Limiting the use of chemicals that damage the stratospheric ozone layer in order to prevent increased levels of harmful ultraviolet radiation. c) Current version of Clean Air Act established a series of detailed control requirements that the federal government implements and the states administer. 1) Require all industries to obtain permits to release materials into the air. 2) All new and existing sources of air pollution were subject to national ambient air quality standards established for SO2, NO2, PM, CO, O3 and Pb. 3) New sources were subject to more stringent control technology and permitting requirements than existing facilities. 4) Hazardous air emissions were regulated: 189 substances are regulated

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5) Power plants were allowed to sell their SO2 release permits to other companies. This program encourages power plants that can easily reduce their emissions to do so. The net result of this program has reduced SO2 at a rapid rate than was anticipated. 6) A program for the phase-out of ozone-depleting substances (CFCs, halons, carbon tetrachloride, and methyl chloroform) was established. ACID DEPOSITION 1. The accumulation of potential acid-forming particles, being dissolved in rain, snow, or fog, on a surface. They can also be deposited as dry particles, which turn into acids when mix with water. All of the sources of acid-forming particles are commonly referred to as acid rain. 2. Acids result from natural causes, such as vegetation, volcanoes, and lightning, and from human activities, such as burning of coal and use of the internal combustion engine (Fig. 16.11). The combustion produces SO2 and NOx, which are then oxidized by oxidizing agents such as ozone, hydroxide ions, or hydrogen peroxide, along with water to convert sulfur dioxide to sulfuric acid and nitrogen oxide to nitric acid. 3. Acid rain, mainly caused by SOx and NOx, is a worldwide problem: high acid rain damage occurs in Canada, England, Germany, France, Scandinavia, and the U.S. Rain is normally slightly acidic (pH = 5.6 ~ 5.7) since atmospheric carbon dioxide dissolves in water to produce carbonic acid. But rain sometimes has pH thousand times greater than the normal range. Ex. In 1969, New Hampshire had a rain with a pH of 2.1. In 1974, Scotland had a rain with pH of 2.4. Currently, rain in much of the northern U.S. and parts of Ontario has a pH of ~4.5. 4. Damages caused by acid rain: a) Buildings and monuments: They are made by limestone (calcium carbonate, CaCO3), which reacts with sulfuric acid to produce calcium sulfate (gypsum, CaSO 4), which is more soluble than calcium carbonate. (Fig.16.12). b) Metal surface is also attacked by acid rain as most of the metals can dissolve/react with acid to produce hydrogen gas. c) In some parts of the world, acid rain has is suspected of causing the death of many forests and reducing the vigor and rate of growth of others, such as in central Europe and northeastern U.S., especially for red spruce trees at higher elevations. A strong correlation between acid rain and the decline of forests:  The deposition of acids cause major changes to the soils in areas where the soils are not able to buffer the additional acid. As the soil become more acidic, aluminum I released from building sites and becomes part of the soil water, where it interferes with the ability of plant roots to absorb nutrients.  Reduction in the pH of the soil may also change the kinds of bacteria in the soil and reduce the availability of nutrients for plants.  Though each of the factor can not cause trees to die, each could add to the stresses on the plant and may allow other factors, such as insect infestations, extreme weather conditions (particularly at high elevations), or drought, to further weaken trees and ultimately cause their death. d) The effects of acid rain on aquatic ecosystems are more clear-cut: as the lakes become more acidic, there was a progressive loss of many kinds of organisms. The food web becomes less complicated, many organisms fail to reproduce, and many others die. Most healthy lake has a pH > 6. At pH = 5.5, many desirable species are eliminated. At pH = 5, only a few starving fish many be found, and none is able to reproduce. Lakes with a pH = 4.5 are nearly sterile. OZONE DEPLETION 1. In 1985, it was discovered that a significant thinning of the ozone layer over the Antarctic occurred during the Southern Hemisphere spring; this area became known as “ozone hole”. Some regions of the ozone layer showed 95% depletion. Several countries became involved in efforts to protect the ozone layer, which absorbs the UV light.

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2.

UV O3 -------------- O2 + O UV O2 -------------- 2O O2+ O -------- O3

Less ozone in the upper atmosphere would result in more UV reaching the Earth’s surface, causing skin cancers and cataracts in humans and increased mutations in all living things. 3. How chlorofluorocarbons destroy/reduce the ozone layer in the upper atmosphere? UV Cl2 -------------- 2Cl Cl + O3 -------- ClO + O2 ClO + O ------- Cl + O2 It may take 10 to 20 years for chlorofluorocarbon molecules to get into the stratosphere, and then they can react with the ozone for up to 120 years. 4. In 1970s, the U.S., Canada, Norway, and Sweden banned chlorofluorocarbons used in aerosol cans, and the European Union agreed to reduce use of chlorofluorocarbons in aerosol cans. However, in the other parts of the world, chlorofluorocarbons are still widely used as aerosol propellants. 5. The major barrier to reduce chlorofluorocarbons is the reluctance of the developed countries of the world to establish a fund to help less-developed countries implement technologies that would allow them to obtain refrigeration and air conditioning without the use of chlorofluorocarbons. 6. In 1991, DuPont announced the development if new refrigerants not harm the ozone layer. These and other alternative refrigerants are now used in refrigerators and air conditioners in many nations. In 1996, the U.S. has stopped producing chlorofluorocarbons. GLOBAL WARMING AND CLIMATE CHANGE 1. Greenhouse gases (Fig. 16.7 and Table 16.2) include carbon dioxide, methane, chlorofluorocarbons (mainly CCl3F and CCl2F2), and nitrous oxide (N2O). These gases let sunlight enter the atmosphere but slow the loss of heat from the Earth’s surface. Computer simulations as well as with more gathered date of climate indicate that global temperatures will rise as atmospheric concentrations of greenhouse gases increase. 2. It’s difficult for general public to relate to these changes or see evidence of them since each of us experiences only our own local weather and climate, and we observe more short-term patterns, while the computer models are attempting to predict the long-term trends for large regions of the Earth. 3. The conclusions made by IPCC (Intergovernmental Panel on Climate Change) are o o a) The average temperature of the Earth has increased 0.3 – 0.6 C (0.5 – 1.0 F) in the past 100 years. 1998 was the warmest year on record, 2005 was the second, and 2002 was the third. During the same period, the sea level has risen 10 – 25 cm (4 – 10 inches). (Fig. 16.6) b) A strong correlation exists between the increase in temperature and the concentration of greenhouse gases in the atmosphere. c) Human activity greatly increases the amounts of these greenhouse gases. Causes of Global Warming and Climate Change 1. What actually causes global warming? Several gases in the atmosphere are transparent to UV and visible light but absorb Infrared radiation (IR). These gases allow sunlight to penetrate the atmosphere and be absorbed by the Earth’s surface. This sunlight energy is radiated as IR (heat) and is absorbed by greenhouse gases in the atmosphere. Because the effect is similar to what happens in a greenhouse (the glass allows light to enter but retards the loss of heat), these gases are called greenhouse gases, and the warming thought to occur from their increase is called the greenhouse effect. 2) Carbon dioxide: the most abundant of the greenhouse gas.

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a) It occurs as a natural consequence of respiration. However, much larger quantity release into the atmosphere as a waste product of energy production from fossil fuels(human activity). b) Another contributing factor is the deforestation. Threes and other vegetation remove carbon dioxide from atmosphere through photosynthesis. Cutting down trees to convert forested land to other use releases this carbon, and the reduction in the amount of forest lessens its ability to remove carbon dioxide from the atmosphere. The combination of fossil-fuel burning and deforestation has resulted in an increase in the concentration of carbon dioxide in the atmosphere. 3) Methane: mainly from biological sources, although some enters the atmosphere from fossil fuel sources. a) Several bacteria in the wetland and rice fields release methane into the atmosphere. Methane-releasing bacteria are found in the guts of termites and various kinds of ruminant animals such as cattle. b) Control of methane sources is unlikely because the primary sources involve agricultural practices that would be very difficult to change and neither is likely to occur because food production in most parts of the world needs to be increased, not decreased. 4) Nitrous oxide: a minor component of the greenhouse gas. It enters the atmosphere primary from the fossil fuels and fertilizers. It can be reduced by more careful use of nitrogen-containing fertilizers. 5) Chlorofluorocarbons (CFCs): A minor component of the greenhouse gas and are entirely the result of human activity. a) CFCs are widely used as refrigerant gases in refrigerators and air conditioners, as cleaning solvents, and as expanders in foam products. b) Though they are present in the atmosphere in minute quantities, they are extremely efficient as greenhouse gases (~15,000 times more efficient at retarding heat loss than is carbon dioxide). Potential Consequences of Global Warming and Climate Change: Effects of global warming (Fig. 16.19) 1) Poor nations are generally more vulnerable to the consequences if global warming. These nations tend to be more dependent on climate-sensitive sectors, such as subsistence agriculture, and lack the resources to buffer themselves against the changes that global warming may bring. IPCC has identified Africa as the “content most vulnerable to the impacts of projected changes because widespread poverty limits adaptation capabilities”. 2) Other consequences of global warming and change of climate: rising sea levels, disruption of the hydrologic cycle, potential; health concerns, changing forests and natural areas, and challenges to agriculture and the food supply. a) Rising sea level erodes beaches and the melting glaciers would add more water to the oceans. The oceans will continue to expand for several centuries after temperatures stabilize. CO2 level (ppm) Sea level increases Health effects 550 (double pre100 cm (or 39.4 inches) Heat wave events six industrial levels) times more frequently 1100 200 cm (or 78.7 inches) b) Disruption of hydrologic cycle:  Increasing temperature increases evaporation and causes some areas drier and some areas more rainfalls.  Lower river flows and lake levels could impair navigation, hydroelectric power generation, and water quality, and reduce the supplies of water available for agricultural, residential, and industrial uses.  Some areas may experience more flooding in water and spring, as well as lower supplies during summer.  More generally, the tendency for rainfall to be more concentrated in large storms as temperatures rise would tend to increase river flooding, without increasing the amount of water available. It’s more difficult to predict the effects of changes in the hydrologic cycle. But the concerns are focused on navigation, hydropower, water supply and demand, flood control, environmental quality and recreation, and political issues (typically in Middle East and Africa,

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which can raise tensions among countries that depend on water supply originating outside their borders). c) Health effects:  Heat exhaustion and some respiratory problems increase.  Higher air temperature increases the concentration of ozone at ground level, which leads to injury of lung tissue and intensifies the effects of airborne pollen and spores that cause respiratory diseases, asthma, and allergic disorders. Children and elderly are most vulnerable. d) Changing forests and natural areas:  Climate change could dramatically alter the geographic distributions of vegetation types. The composition of one-third of the Earth’s forests could undergo major changes as a result of climate changes associated with a carbon dioxide level of 700 ppm.  Sugar maples in northeastern U.S. and the Everglades system in Florida both disappear in modeling forecasts. Wetlands and coral reefs may also undergo radical decline due to climate change. These kinds of changes would result in an accelerated loss of species and an additional challenge to efforts to protect biological diversity.  The more gradually climate changes, the easier it could be for species to adapt. As a result, ecologists have proposed that emission constraints be calculated so as to limit the rate of o o warming to no more than 0.1 C (0.18 F) per decade. e) Challenges to agriculture and the food supply:  Climate strongly affects crop yields: a carbon dioxide concentration of 550 ppm is likely to increase crop yields in some area by as much as 30-40%, but it will decrease yields in other places by similar amounts, even for the same crop.  A warmer climate would reduce flexibility in crop distribution and increase irrigation demands. It can also expand the range of pests and result in greater use of pesticides. Despite these effects, total global food production is not expected to be altered substantially by climate change, but negative regional impacts are likely.  The poorest countries many already subject to hunger are the most likely to suffer significant decrease in agricultural productivity. f) Unanticipated changes  Scientists have hypothesized many troubling possibilities, including more frequent or severe hurricanes and a shift in the ocean currents responsible for moderating the climate of north Europe.  The most serious effects of climate change also may lie outside current calculation. The evolution of a common international scientific understanding of such complex issues has been a critical step toward addressing the problem, just as with the problem of ozone depletion. ADDRESSING CLIMATE CHANGE It involves technological change, political will and economic realities. a) Energy efficiency  A major step toward slowing global warming would be to increase the efficiency of energy utilization.  More efficient use of fuels converse the shrinking supplies of energy resources.  One way to stimulate a move toward greater efficiency would be to place a tax on the amount of carbon individuals and corporations releases into the atmosphere. This would increase the cost of fuels and the demand for fuel efficiency because the cost of fuel would rise. It would also stimulate the development of alternative fuels with a lower carbon content and generate funds for research in any aspects of fuel efficiency and alternative fuel technologies. b) The role of biomass  Another approach is to increase the amount of carbon dioxide removed from the atmosphere. If enough of biomass is present, the excess carbon dioxide can be used by vegetation during photosynthesis, thereby reducing the impact if carbon dioxide released y fossil-fuel burning.  Many critics argue that this approach will provide only a short-term benefit, since the trees will mature and die and their decay release carbon dioxide into the atmosphere at some later time.  Another concern is the destruction of vast areas of rainforest in tropical regions of the world. These ecosystems are extremely efficient at removing carbon dioxide and storing the carbon atom in plant structures.

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 Grazing lands and farms in such regions of the world are often abandoned after a few years and do not return to their original forest condition. c) Political and economic forces:  The phasing out of chlorofluorocarbons, also an greenhouse gas, required significant technological changes, but the changes were very rapid once a broad consensus was reached and a plan established. Changes made to protect the ozone layer have had the side benefit of reducing the release of a potent greenhouse gas.  It will be more difficult to achieve s similar consensus to reduce carbon dioxide emissions because carbon dioxide is released as a result of energy consumption, and the energy consumption affects all parts of the economy.  The fundamental benefit of cleaner and more energy-efficient production potentially could encourage changes to industry, energy production, and transportation that would result in lower carbon dioxide releases.  Increases in energy efficiency and reductions in greenhouse gas emissions are likely to have important related benefits that could offset the costs by lowering health care costs and higher worker productivity. Also improved energy efficiency also reduces the need for new power plants and released energy infrastructure.  Resources and policies to increase investment in renewables and other long-term technologies will be needed. INDOOR AIR POLLUTION 1) Growing scientific evidence indicates the indoor air quality can be as worse as or even worse than the outdoor air quality. Many indoor air pollutants and pollutant source are thought to have an adverse effect on human health. 2) Indoor air pollutants include asbestos, formaldehyde (associated with certain wood products and aerosols), airborne pesticide residues, chloroform, perchloroethylene (associated with dry cleaning), paradichlorobenzene (from mothballs and air fresheners), and many disease-causing or allergy-producing organisms. 3) Smoking is the most important air pollutant source in the U.S. in terms of human health. It’s estimated 350,000 die each year from emphysema, heart attacks, strokes, lung cancer, or other diseases caused by tobacco smoking. Banning smoking probably would save more lives than would any other pollution-control measure. 4) A recent contributing factor to the concern about indoor air pollution is the weatherizing of buildings to reduce heat loss and save on fuel costs. In older homes, a complete exchange of air occurs every hour as the fresh air leaks in around doors and windows and through cracks and holes in the building. A more energy efficient home tends to trap air pollutants. 5) Though we spend on average almost 90% of our time indoors, the movements to reduce indoor air pollution lag behind regulations governing outdoor air pollution. Secondhand smoke: (Table 16.5: secondhand smoke and toxicity) 1) Many nonsmoking people are exposed to environmental tobacco smoke (secondhand smoke) because they live and work in spaces where people smoke. EPA estimates there are approximately 3000 nonsmokers die each year of lung cancer as a result of breathing air that contains secondhand smoke. Young children exposed to secondhand smoke are much more likely to have respiratory infections. 2) In July 1993 EPA made several recommendations to protect people from secondhand smoke. California has some of the most restrictive smoking laws in the U.S. In 1998, California passed a no-smoking law that effectively banned all smoking in indoor public places, including restaurants and bars. Washington State passed a similar law in 2005 with 2/3 voters supported it. Radon 1) History: In 1985, the engineer at the Limerick Nuclear Generation Station in Pottstown, PA registered a high radiation level. Initially, it was believed that the generating station was the 222 source, however, the subsequent studies indicated that Rn from the engineer’s home was the source. Following the incident, interest in radon and its effects has increased.

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2) The source of radon is U, a naturally occurring element that makes up about 3ppm of 238 206 Earth’s crust. U undergoes 14 steps of decay to become a stable Pb. Radon, an inert gas has a half-life of 3.8 days, is one of the products formed during this process. 222 3) Rn does not enter into any chemical reactions within the body but it can be inhaled. Once in the lung, it may undergo radioactive decay: 222 218 214 214 Rn  Pu (t1/2 = 3 min) + α Pb (t1/2 = 27 min) + α  Bi (t1/2 = 20 min) + r 214 6  Po (t1/2 = 10 s) + r These solid materials remain in the lungs and are chemically active. 4) Increased incidence of lung cancer is the only known health effect associated with radon decay products. It is estimated the decay products of Rn are responsible for about 15,000 lung cancer death annually. (Table 16.6: Rn risk evaluation chart) 5) Rn is formed in the rocks, it usually diffuses up through the rock and soil and escapes harmlessly into the atmosphere. It can also diffuse into groundwater. Rn usually enters a home through an open space in the foundation. 6) About 10% of the homes in U.S. have a potential radon problem. (Fig. 16.22). EPA and the U.S. surgeon general recommend that all Americans (other than those living in apartment buildings above the second floor) test their homes for radon. If Rn level reaches 4 pCi/L, the EPA recommends homeowner take action to lower the level. Usually it is not expensive and consists of blocking the places where Rn is entering or venting Rn sources to the outside. Noise Pollution 1) Noise refers to as unwanted sound. Exposure to noise can caused physical, as well as mental, harm. 2) The loudness of noise is measured by decibles (db). Decible scales are logarithmic. 3) The frequency or pitch of a sound is also a factor in determining its degree of harm: highpitched sounds are the most annoying. The most common sound pressure scale for high-pitched sounds is the A scale, and its unit is written “ dbA”. 4) Hearing loss begins with prolonged exposure (8 hours or more per day) to 80 or 90 dbA levels of sound pressure. Sound pressure becomes painful at around 140 bdA and can kill at 180 dbA. (Table 16.7) 5) Noise pollution also links to nervous tension headachesneuroses. It can also cause blood vessels to constrict (which reduce blood flow to key body parts), disturbs unborn children, and sometimes causes seizures in epileptics. 6) In U.S., The Noise Control Act of 1972 was the first major attempt to protect the public health and welfare from detrimental noise. 7) Several European countries have developed quiet construction equipment in conjuction with strongly enforced noise ordinances. The Germans and Swiss have established maximum day and night noise levels for certain areas.

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