3IntroductionWe could live about a month without food. We could even live for several days without water. But without air, we cannot live more than a few minutes.We might foul the air so badly in some places that it could become unfit to breath. In some areas, the air is so bad that people become sick from breathing it, and some even die because of it.The World Health Organization estimates that a billion people live in places where the air is substandard and that air pollution kills 8,000 people a day worldwide. About 90% of the deaths occur in developing countries.
5What is air pollution? Is fart or bad breath air pollution? Air pollution is the contamination of air by the discharge of harmful substances.
6Indoor Pollutions There are many sources of indoor air pollution. Tobacco smokecookingheating appliancesvapors from building materials, paints, furnitureother materials within the home that emit unhealthy chemicals
7ExplanationWhile air pollution is thought to be a problem related to outdoor air, the same pollutants can be found indoors. We spend up to 60% of our time indoors and our homes are not always the safe places we would like them to be.These chemicals, some of which are called volatile organic compounds (VOC) can cause ill health and they are found in carpets, chipboard, furnishing fabrics, clothing pesticides, cleaning products, toiletries, cosmetics and hobby products.Pollution exposure at home and work is often greater than outdoors. The California Air Resources Board estimates that indoor air pollutant levels are 25-62% greater than outside levels and can pose serious health problems.
9Explanation-CarsCars are wonderful things. You can go where you want and when. You can travel with friends or family in a weatherproof lounge-room on wheels that whisks you along far faster than you could run. But they do create air pollution.Lead in petrolLead is put in petrol to make older designs of car engine work better – but if it gets into your body it will have the opposite effect. The lead comes from the exhausts of cars running on leaded petrol and it is poisonous stuff. Babies and young children can be badly affected by lead – because it can stop their nervous systems developing properly and it can damage their brains. Once lead has found its way into your body it is difficult to get it out again, so it is obviously better to keep it out in the first place. Changing from leaded to unleaded petrol has already helped reduce the problems caused by lead poisoning. But one of the problems is that Australians tend to keep their cars for a very long time, so although unleaded petrol is used in all cars less than 10 years old, it will take a while for all the old cars using leaded petrol to vanish from our roads.Photochemical smogPhotochemical smog (where ozone is generated) is the main air pollution problem in the larger Australian cities, because of our sunny weather. It is caused by the release of nitrogen oxides, mainly from motor vehicles. Under the influence of sunlight, these oxides react with certain hydrocarbon compounds to form various substances that are toxic to humans and plants. The smog irritates people's eyes, nose and throat, causing considerable discomfort.Ozone is an extremely irritating and poisonous gas, and concentrations in our cities can exceed recommended health limits for short periods during photochemical smog episodes. The air circulation patterns in some of our cities (where polluted air may recirculate for some time before being swept away) worsen the problem.(Ozone levels are rising in the lower atmosphere; the destruction of ozone in the upper atmosphere is a quite separate problem, see our Nova topic Earth's sunscreen – the ozone layer.)All of this is bad news for us and bad news for the planet – so what are we doing about it?Catalytic convertersDevelopment of catalytic converters has helped reduce pollutants in car exhaust. The converter is a special box that goes onto a car's exhaust system just past the engine. It is sealed on the outside, but inside is a heat-proof block with lots of holes through it – a bit like a big bundle of hollow spaghetti. As the car's hot exhaust gases pass through this honeycomb of holes, they come into contact with a thin coating of precious metal – usually platinum. This coating causes chemical changes to take place in the exhaust gases, which much reduce the pollutants coming out of the car.But as more and more cars take to the road, even these much cleaner cars are still a major source of pollution. Also, using a precious metal like platinum makes the converters very expensive to produce.
10Explanation-Natural Pollution Even before there were people, there were air pollution. Wildfires, windblown dust, and volcanic eruptions added pollutants to the atmosphere, and they still do so. Volcanoes spew ash and poisonous gases into the atmosphere.Example: In 1995 eruptions of the Soufriere Hills volcano on Montserrat covered much of the Caribbean island with ash. The ash and fear of further eruptions caused the evacuation of more than half the country.Dust storms, especially in arid regions, add massive amounts of particulate matter to the atmosphere.
11Explanation-Burning of Coal Air Pollution in ChinaAs China strives to become an industrial power, its people are paying a heavy price in pollution. Coal burning supplies about ¾ of China’s commercial energy needs. The coal has a high sulfur content, and emission controls are often inadequate. As a result, levels of sulfur dioxide and particulate matter are among the highest in the world. About half of China’s largest cities have SO2 levels above the WHO guidelines. Some cities, such as Lanzhou and Taiyuan, have levels almost 10 times the WHO standard. All but 2 of 82 cities monitored exceeded WHO guidelines for particular matter.China’s growing fleet of motor vehicles also contributes to air pollution problems. Most vehicles are operated in large cities, and because few have effective emission controls, they contribute heavily to the smog in these cities.China is beginning to attack the problem by closing heavily polluting factories in some larger metropolitan areas. The Chinese government has also invested in gas and in cleaner, more efficient briquettes as replacements for raw coal as a fuel for domestic cooking and heating.
12Major Air Pollutants Carbon Monoxide (CO) CO Carbon Dioxide (CO2) Chlorofluorocarbons (CFCs)Hazardous Air Pollutants (HAPs)Ozone (O3 )Nitrogen Oxide (NOx)
13Explanation-major pollutants Carbon Monoxide (CO) is an odorless, colorless gas. After being inhaled, CO molecules can enter the bloodstream, where they inhibit the delivery of oxygen throughout the body. Low concentrations can cause dizziness, headaches, and fatigue; high concentrations can be fatal.CO is produced by the incomplete burning of carbon-based fuels, including gasoline, oil, and wood. It is also produced from incomplete combustion of natural and synthetic products, such as cigarette smoke. It can build up in high concentrations in enclosed areas such as garages, poorly ventilated tunnels, and even along roadsides in heavy traffic.Carbon Dioxide (CO2) is the principal greenhouse gas emitted as a result of human activity (e.g., burning of coal, oil, and natural gas). CO2 can cause burns, frostbite, and blindness if an area is exposed to it in solid or liquid form. If inhaled, it can be toxic in high concentrations, causing an increase in the breathing rate, unconsciousness, and death.Chlorofluorocarbons (CFCs) are chemicals used in great quantities in industry, for refrigeration and air conditioning, and in consumer products. CFCs, when released into the air, rise into the stratosphere (a layer of atmosphere high above the Earth). In the stratosphere, CFCs take part in chemical reactions that result in reduction of the stratospheric ozone layer, which protects the Earth's surface from the sun. Reducing the release of CFC emissions and eliminating the production and use of ozone-destroying chemicals is very important to the Earth's stratosphere.Hazardous Air Pollutants (HAPs) are chemicals that cause serious health and environmental effects. Health effects include cancer, birth defects, nervous system problems, and death due to massive accidental releases, such as the disaster that occurred at a pesticide plant in Bhopal, India.Hazardous air pollutants are released by sources such as chemical plants, dry cleaners, printing plants, and motor vehicles including cars, trucks, buses, planes.
14Explanation-major pollutants cont.d Lead is a highly toxic metal that produces a range of adverse health effects particularly in young children. Lead can cause nervous system damage and digestive problems, and some lead-containing chemicals cause cancer. Lead can also harm wildlife.Lead has been phased out of gasoline, which has considerably reduced the contamination of air by lead. However, lead can still be inhaled or ingested from other sources. The sources for lead include paint (for houses and cars), smelters, manufacture of lead batteries, fishing lures, certain parts of bullets, some ceramic ware, miniblinds, water pipes, and a few hair dye products.Ozone (O3 is a gas that is a variety of oxygen. Oxygen consists of two oxygen atoms; ozone consists of three. Ozone in the upper atmosphere, where it occurs naturally in what is known as the ozone layer, shields the Earth from the sun's dangerous ultraviolet rays. However, at ground level where it is a pollutant with highly toxic effects, ozone damages human health, the environment, crops, and a wide range of natural and artificial materials. Ground-level ozone can irritate the respiratory tract, cause chest pain, persistent cough, an inability to take a deep breath, and an increased susceptibility to lung infection. Ozone can damage trees and plants and reduce visibility.Ground-level ozone comes from the breakdown (oxidation) of volatile organic compounds found in solvents. It is also a product of reactions between chemicals that are produced by burning coal, gasoline, other fuels, and chemicals found in paints and hair sprays. Oxidation occurs readily during hot weather. Vehicles and industries are major sources of ground-level ozone.Nitrogen Oxide (NOx) is a major contributor to smog and acid rain. Nitrogen oxides react with volatile organic compounds to form smog. In high doses, smog can harm humans by causing breathing difficulty for asthmatics, coughs in children, and general illness of the respiratory system. Acid rain can harm vegetation and run into lakes and rivers which changes the chemistry of the water, and makes it potentially uninhabitable for all but acid-tolerant bacteria.Nitrogen oxides are produced from burning fuels, including gasoline and coal. (NOx) acid aerosols can reduce visibility.
18Effects of Air Pollution Air pollution can cause health problems including burning eyes and nose, itchy irritated throat, and breathing problems. Some chemicals found in polluted air can cause cancer, birth defects, brain and nerve damage, and long-term injury to the lungs and breathing passages in certain circumstances. Above certain concentrations and durations, certain air pollutants are extremely dangerous and can cause severe injury or death.Air pollution can also damage the environment and property. Trees, lakes, and animals have been harmed by air pollution. Air pollution has thinned the protective ozone layer above the Earth. Air pollution can damage buildings, monuments, statues, and other structures.Air pollution also can result in haze, which reduces visibility in national parks and elsewhere, and can sometimes interfere with aviation.
19Effects of Air Pollution Global Warming– the increased concentration of carbon dioxide and other greenhouse gases in the atmosphere lead to rise in earth’s average temperature.OzoneGreenhouse EffectAcid Rain comes mainly from sulfur dioxide emitted from power plants and smelters and from nitrogen oxides discharges from power plant and automobiles. These acids are often carried far before falling as rain or snow. Acids corrode metals and even erode stone buildings and statues.