Air Pollution APES – Period 5 Jane Kim Janet Hong Lynn Yi Exosphere Thermosphere Mesosphere Stratosphere Troposphere Primary pollutants: are mixed vertically and horizontally and are dispersed and diluted by the churning air in the troposphere. Ex: CO, CO2, SO2, NO, NO2, most hydrocarbons, and most suspended particles Secondary pollutants: while in the troposphere, some of the primary pollutants may react with one another or with the basic compounds of air. Ex: SO3, HNO3, H2SO4, H2O2, O3, and PANs Six Principal Pollutants - Carbon Monoxide (CO) - Lead (Pb) - Nitrogen Dioxide (NO2) - Ozone (O3) - Particulate Matter (PM-10) - Sulfur Dioxide (SO2) Ozone Ozone is formed by the action of sunlight on carbon-based chemicals known as hydrocarbons, acting in combination with a group of air pollutants called oxides of nitrogen. Ozone reacts chemically ("oxidizes") with internal body tissues that it comes in contact with, such as those in the lung. Ozone (O3) in the troposphere causes more damage to plants than all other air pollutants combined. SO2 Sulfur dioxide belongs to the family of gases called sulfur oxides (SOx ). These gases are formed when fuel containing sulfur (mainly coal and oil) is burned, and during metal smelting and other industrial processes. 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. SO2 Emissions Lead In the past, motor vehicles were the biggest source of lead. But since leaded gasoline has been phased out, lead emissions have decreased by about 98 percent. Today, metal processing is the biggest source of atmospheric lead. Lead can harm the kidneys, liver, nervous system and other organs. It may cause neurological impairments such as seizures, mental retardation and behavioral disorders. Even at low doses, lead is associated with damage to the nervous systems of fetuses and young children, resulting in lowered IQ and learning problems. Particulates Particulates is a general term used to describe tiny bits of matter floating around in the atmosphere, such as certain types of smoke (like diesel smoke), fine ash and dust. Larger particles are caught by the hairs in your nose and your breathing tubes, but smaller particles can get past these defenses and cause lots of trouble. NO2 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. Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections such as influenza. Carbon Monoxide Carbon Monoxide is produced by the incomplete combustion of the fossil fuels – gas, oil, coal and wood used in boilers, engines, oil burners, gas fires, water heaters, solid fuel appliances and open fires. When carbon monoxide is present in the air you breath into your lungs, it attaches itself to the hemoglobin. The bond between hemoglobin and carbon monoxide is 250 times stronger than oxygen. In the lungs carbon monoxide attaches to red blood cells in place of oxygen. Smog (smoke+fog) The Four Most Dangerous Indoor Air Pollutants 1. cigarette smoke 2. Formaldehyde 3. Asbestos 4. radioactive radon-222 gas Formaldehyde Formaldehyde is a colorless liquid or gas with a strong, distinctive odor. It is found in furniture, new carpets, particle board, plywood, rubber cement and adhesives. Low levels of exposure can irritate the eyes, nose and throat, cause skin problems, serious breathing problems and can increase your risk of certain kinds of cancer. ASBESTOS Sources: Deteriorating of damaged insulation, fire-proofing, or acoustical materials. Health Effects: No immediate symptoms. Chest and abdominal cancers and lung diseases. Smokers are at higher risk of developing asbestos-induced lung cancer. RADON Sources: Earth, uranium and rock beneath home; well water; building materials. Health Effects: No immediate symptoms. Estimated to cause about 10% of lung cancer deaths. Smokers are at higher risk of developing radon-induced lung cancer. Radon-222 can enter the house by diffusion from soil and by emanation from building materials, tap water and methane gas. Characteristics - an odorless, tasteless, invisible gas that mixes with air - chemically inert and essentially non-reactive - heaviest noble gas with highest melting and boiling point - highly soluble in non-polar solvents - moderately soluble in cold water - able to diffuse through rock and soil - decays by alpha particle emission (T 1/2 = 3.8 days) The largest source of "indoor air pollution"- in our homes, our schools or workplaces- is car and truck pollution. Electric vehicles are sometimes referred to as "zero-emission vehicles" because they produce essentially no pollution from the tailpipe or through fuel evaporation. This is important, for it means that the use of electric vehicles could greatly reduce emissions of carbon monoxide and smog-forming pollutants in cities with dirty air. Symptoms (IAP) As many as 20 million Americans suffer from: - chronic breathing problems - dizziness - rash - headaches - sore throat - sinus - eye irritation Acid Deposition: the falling of acids and acid-forming compounds from the atmosphere to earth’s surface. Acid deposition is commonly known as acid rain, a term that refers only to wet deposition of droplets of acids and acid-forming compounds Effects of Acid rain - human respiratory disease (bronchitis and asthma) - damages statues, buildings, metals, and car finishes - depletion of calcium and magnesium ions in the soil - damages trees How to reduce acid deposition 1. Reduce energy use and thus air pollution by improving energy efficiency 2. Switch from coal to cleaner burning natural gas and renewable energy resources 3. Remove sulfur from coal before it is burned 4. Burn low-sulfur coal 5. Remove SO2, particulates, and nitrogen oxides from smokestack gases 6. Remove nitrogen oxides from motor vehicle exhaust Sick Building A building is considered “sick” when at least 20% of its occupants suffer persistent symptoms that disappear when they go outside At least 17% of the 4 million commercial buildings in the U.S. are considered “sick”. Ozone Most ozone (about 90%) exists in the stratosphere, in a layer between 10 and 50km above the surface of the earth. This ozone layer performs the essential task of filtering out most of the sun's biologically harmful ultraviolet (UV-B) radiation. Ozone Hole Over Antarctica (and recently over the Arctic), stratospheric ozone has been depleted over the last 15 years at certain times of the year. This is mainly due to the release of manmade chemicals containing chlorine such as CFC's (ChloroFluoroCarbons), but also compounds containing bromine, other related halogen compounds and also nitrogen oxides (NOx). CFC’s CFC's are chemicals that can be used in the refrigerator to help keep food cold. They can also be used in air- conditioning and in products in spray cans. CFC's rise into the air going into a layer called the stratosphere. When this happens, the CFC's take part in chemical reactions that can destroy parts of the ozone which protects us from the sun's dangerous ultraviolet rays. Ozone Hole 1979 1998 Greenhouse Effect The Earth is kept warm by it's atmosphere, which acts rather like a woolly coat - without it, the average surface temperature would be about -18 degrees Centigrade. Heat from the sun passes through the atmosphere, warming it up. As the Earth warms up, it emits heat. Some of this heat is trapped by the atmosphere, but the rest escapes into space. The so-called "greenhouse gases" make the atmosphere trap more of this radiation, so it gradually warms up more than it should, like a greenhouse. Greenhouse Effect Greenhouse Effect Ozone Shield Where in the atmosphere Troposphere Stratosphere does it occur? What process occurs? Traps heat near the earth’s Filters ultraviolet (UV) surface radiation from the sun What natural gases are Water(H2O), carbon Oxygen(O2), ozone(O3) involved? dioxide(CO2), methane(CH4) What are important Carbon dioxide(CO2), Chlorofluorocarbons human inputs? methane (CH4), (CFCs), halons, carbon chlorofluorocarbons (CFCs), tetrachlorine, methyl nitrous oxide(N2O) choloroform (stable), halogen-containing gases What problems result? Global warming Ozone depletion Carbon Dioxide Carbon dioxide is produced when any form of carbon or almost any carbon compound is burned in an excess of oxygen. For example, it is released into the atmosphere during natural forest fires and the man-made combustion of fossil fuels. Other natural sources of carbon dioxide include volcanic eruptions, decay of dead plant and animal matter, evaporation from the oceans and respiration (breathing). Methane Methane is a greenhouse gas that is creating a serious problem for global warming. Methane gases are very potent when trapping infrared heat in the atmosphere, because one molecule of methane can trap infrared heat twenty times more than carbon dioxide. Methane the second most important greenhouse gas is mostly produced by the digestive system of cows. Asthma Smog and particles certainly trigger attacks in some people who already have asthma. For a long time it was thought that air pollution could not cause asthma to develop in previously healthy people. Some recent experiments challenge this belief. Scientists have shown that people exposed to ozone or nitrogen dioxide are more likely to react to allergens such as grass pollens and housedust mites than those who are not exposed. Thus a combination of air pollution and allergens could cause some cases of asthma. Lung Cancer Lung cancer is more common in cities than in the country. We know that over 90% of lung cancers are caused by smoking cigarettes. A radioactive gas called radon is thought to cause about 7% of lung cancers in North America. 87% of lung cancer cases are caused by smoking. 12 percent of all lung cancer deaths are linked to radon. Another leading cause of lung cancer is on-the-job exposure to cancer-causing substances or carcinogens. Air pollution can make you sick. It can cause burning eyes and nose and an itchy, irritated throat, as well as trouble in breathing. Some chemicals found in polluted air cause cancer, birth defects, brain and nerve damage and long-term injury to the lungs and breathing passages. Some air pollutants are so dangerous that accidental releases can cause serious injury or even death. According to the U.S. Environmental Protection Agency's (EPA) latest Ten-Year Air Quality and Emissions Trends report, there have been significant reductions in all 6 criteria pollutants and reductions are expected to continue. The 1990 Clean Air Act Under this law, EPA sets limits on how much of a pollutant can be in the air anywhere in the United States. This ensures that all Americans have the same basic health and environmental protections. The law allows individual states to have stronger pollution controls, but states are not allowed to have weaker pollution controls than those set for the whole country. Chapter 19: Global Warming and Ozone Loss Jane S. Kim Janet Hong Lynn Yi Period 5, APES The Greenhouse effect • In the Greenhouse effect, certain gases in the atmos phere trap heat in the trop osphere (lower atmospher e). • If the atmospheric concent rations of these gases rise and arent removed by othe r processes, the average t emp of the lower atmosph ere will gradually increase. Greenhouse gases • The major greenho • These gases remai use gases are wate n in the atmospher r vapor (H20), carb e for 2,000-50,000 on dioxide (C20), o years. zone (o3), methane (CH4), nitrous oxid • The two predomina e (N2O), and chlor nt gases are water ofluorocarbons (CF vapor (hyrologic cy Cs), and a recently cle) and carbon dio identified perfluoro xide (global carbon carbons (PFCs) cycle) Global warming • Measured atmospheric levels of certain gre enhouse gases have risen substantially in r ecent decades and are projected to enhan ce the earth’s natural greenhouse effect, a phenomenon called global warming • Most of the increased levels of these green house gases since 1958 have been caused by human activities such as burning fossil f uels, agricultue, deforestation, and use of CFCs. • Carbon dioxide (CO2): – Responsible for 50-60% of the global warming fr om greenhouse gases produced by human activit es – Main sources are fossil fuel burning (70-75%) an d land clearing and burning (20-25%) – Remains in atmosphere for 50-200 years • Chloroflurocarbons (CFCs): – Contribute to global warming in the troposphere and also deplete ozone in the stratosphere – Main sources are leaking ACs and fridges, evap oration of industrial solvents, production of plas tic foams, and aerosol propellants – Trap 1,500- 7,000 times as much heat per mol ecule as CO2 while they are in the troposphere. • Methane (CH4): – Accounts for about 20% of the overall warming eff ect – Produced when anaerobic bacteria break down de ad organic matter in moist places that lack oxygen . – Stays in the troposphere for 9-15 years – Each CH4 molecule traps 20 times as much heat a • Nitrous oxide (N2O): – Can trap heat in the troposphere and also deplete oz one in the stratosphere – Released from nylon production, burning of biomass and nitrogen-rich fuels, smog-fighting catalytic con verters on motor vehicles, and the breakdown of nitr ogen fertilizers in soil, livestock wastes, and nitrate- contaminated groundwater. – Stays in the troposphere about 120 years. • According to EPA, emission of green house gases by the US rose by 20% between 1990 and 1996. Energy rela ted activities accounted for about 86 % of these emissions in 1996, mostly through burning fossil fuels. • The atmospheric concentrations of C O2 and other greenhouse gases are p rojected to double from preindustrial l evels sometimes during the next cent ury and then continue to rise The Earth’s past temperature s • Since 1860, mean global temperature after correcting for excess heating ov er urban areas has risen 0.3-0.6 degr ees Celsius. • Temperature rose about 0.3 degrees between 1846 and 1997 • Since 1860, the thirteen warmest year s occurred between 1979 and 1998, with 1990, 1995, 1997, and 1998 bein g the four hottest years. Future global warming and its ef fects • According to the la • According to the m test climate models odels, the northern , the earth’s mean hemisphere should surface temperatur warm more and fas e should rise 1- 3. 5 degrees celsius b ter than the souther etween 1990 and 2 n hemisphere beca 100. use the latter has • Model projects that more heat- absorbi once the climate c ng ocean than land hanges, it will conti and because water nue for hundreds o cools more slowly t f years. han land. How Earth’s climate is affect ed by various factors • Solar output: ups and downs in solar output can temporarily warm or cool t he earth and thus affect the projectio ns of climate models. – Two studies showed that the projected warming power of greenhouse gases sh ould outweigh the climatic influence of t he sun over at least the next 50 years. • Oceans: the oceans might amplify gl obal warming by releasing more CO2 into the atmosphere or might dampen it by absorbing more heat. The ocea ns currently help moderate troposphe ric temperature by removing about 29 % of the excess CO2 pumped into th e atmosphere • Water vapor content and clouds: cha nges in the atmosphere’s water vapor content and the amount and types of cloud cover also affect climate. Warm er temperatures would increase evap oration and the water-holding capacit y of the air and create more clouds. Significant increase in the water vapo r, a potent greenhouse gas, could en hance warming (positive feedback). • Polar ice: the ability of the earth’s surface to reflect light is called its albedo. Becaus e of their albedo, light-colored Greenland and Antarctic ice sheets act like enormous mirrors, reflecting sunlight back into space . If warmer temperatures melted some of t his ice and exposed darker ground or ocea n, more sunlight would be absorbed and w arming would be accelerated. • Air pollution: pollutants in the lower tropos phere can either warm or cool the air depe nding on the reflectivity of the underlying s urface. • It is hypothesized that SO2 and tiny particl es in the troposphere attract enough water molecules to form condensation nuclei, wh ich leads to increased cloud formation Some possible effects of a warmer world • Food production: a warmer global climat e could increase food production in some areas and lower it in others, depending o n crop- growing capacity and climate bel ts. • Water supply: global warming would redu ce water supply, shrinking or completely drying up lakes, streams, and aquifers. • Forests and biodiversity: global warming would change the makeup and location o f many of the worlds forests Continued… • Sea levels: in a warmer world, sea levels a re expected to rise, primarily because ocea n water expands when heated and becaus e some land-based glacial ice will melt • Weather extremes: as more heat is retaine d in the earth’s climate system, more air wi ll move across the earth’s surface. • Human health: global warming would bring more heat waves, which would double or tr iple heat-related deaths among the elderly and people with heart disease; it would als o increase suffering from respiratory ailme nts such as asthma and bronchitis. Solutions: dealing with global warm ing • Stabilizing the Co2 levels at the curre ct level would require reducing curren t global CO2 emissions by 66-83%. • Increased use of nuclear power to re duce the amount of CO2 per unit of e lectricity as coal • Using natural gas could help make th e 40 to 50 year transition to an age of energy efficiency and renewable ener gy. Ozone depletion • In a band of the stratosphere 17- 26 kms abov e the earth’s surface, oxygen is continually con verted to ozone and back to oxygen by a seque nce of reactions initiated by UV radiation from t he sun. • UV radiation reaching the stratosphere consists of three bands: A, B, and C. The ozone layer b locks out nearly all of the highest- energy and biologically damaging UV-B band. • Ozone depletion by certain chlorine- and bromi ne- containing chemicals emitted into the atmo sphere by human activities is a serious long-ter m threat to human health, animal life, and the s unlight drive promary producers that support th • CFCs released into the air rise slowly into the st ratosphere. There, under the influence of high energy UV radiation, they break down and relea se highly reactive chlorine atoms, which speed up the breakdown of highly reactive ozone into O2 and O. This causes ozone to be destroyed f aster than it is formed. Solutions: protecting the ozo ne layer • It will take another 50-60 years for the ozo ne layer to return to 1975 levels and anoth er 100- 200 years to return to pre- 1950 r ecovery levels. • Substitutes are already available for most uses of CFCs. – Hydochlorofluorocarbons (HCFCs) contain fe wer chlorine atoms per molecule than CFCs • Because of their shorter lifetimes in the stratospher e, these compounds should have only about 2.5% of the ozone depleting potential of CFCs.