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China's State Environment Protection Agency (SEPA) is responsible for measuring the level of air pollution in China. As of 28 August 2008, SEPA monitors daily pollution level in 86 of its major cities. The API level is based on the level of 5 atmospheric pollutants, namely sulfur dioxide (SO2), nitrogen dioxide (NO2), suspended particulates (PM10), carbon monoxide (CO), and ozone (O3) measured at the monitoring stations throughout each city.
An individual score is assigned to the level of each pollutant and the final API is the highest of those 5 scores. The pollutants can be measured quite differently. SO2, NO2 and PM10 concentration are measured as average per day. CO and O3 are more harmful and are measured as average per hour. The final API value is calculated per day.
The scale for each pollutant is non-linear, as is the final API score. Thus an API of 100 does not mean twice the pollution of API at 50, nor does it mean twice as harmful. While an API of 50 from day 1 to 182 and API of 100 from day 183 to 365 does provide an annual average of 75, it does not mean the pollution is acceptable even if the benchmark of 100 is deemed safe. This is because the benchmark is a 24 hour target. The annual average must match against the annual target. It is entirely possible to have safe air every day of the year but still fail the annual pollution benchmark.
API and Health Implications (Daily Targets)
The API has been in use in Hong Kong since June 1995. It is measured and updated hourly by the Environmental Protection Department (EPD). Moreover, the EPD makes forecast on the API for the following day everyday.
The API is based on the level of 6 atmospheric pollutants, namely sulfur dioxide (SO2), nitrogen dioxide (NO2), suspended particulates, carbon monoxide (CO), ozone (O3), lead (Pb), measured at all the monitoring stations throughout the territory.
There are 11 General Stations and 3 Roadside Stations. The former includes Central / Western, Eastern, Kwai Chung, Kwun Tong, Sha Tin, Sham Shui Po, Tai Po, Tap Mun, Tsuen Wan, Tung Chung, and Yuen Long; the later Causeway Bay, Central, and Mong Kok.
In Hong Kong, there are two types of API: General API and Roadside API. The EPD reports the latest APIs hourly.
The index and the air quality objectives were set in 1987; and pollutant levels are measured over varying periods, in Î¼g/m3. There are hourly, 24 hour and annual targets for sulfur dioxide and nitrogen dioxide, and 24 hour and annual targets for particulates.
The table below shows the official Health Implications of the respective API levels in Hong Kong.
In 1998, the Education Bureau's recommended schools to curtail outdoor activities when the index reached 200, whereas leading healthcare advocates are urging that the level be revised to 100. The World Health Organisation revised its air quality guideline levels of sulfur dioxide, nitrogen dioxide and ozone in 2006 in light of new scientific evidence. The WHO also introduced new measurement guidelines for very small particulates which are more dangerous to pulmonary function. At the '200' level, Hong Kong levels of SO2 (800Î¼g/m3) and NO2 (1,130Î¼g/m3) are 40 times and 5Â½ times WHO guidelines respectively; the equivalent for particulates (350Î¼g/m3) is 7 times WHO guidelines.
Similar to Hong Kong, the air quality in Malaysia is reported as the API or Air Pollution Index. Four of the index's pollutant components (i.e., carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide) are reported in ppmv but PM10 particulate matter is reported in Î¼g/m3.
This scale below shows the Health classifications used by the Malaysian government.
- 0-50 Good
- 51-100 Moderate
- 101-200 Unhealthy
- 201-300 Very unhealthy
- 301- Hazardous
If the API exceeds 500, a state of emergency is declared in the reporting area. Usually, this means that non-essential government services are suspended, and all ports in the affected area are closed. There may also be a prohibition on private sector commercial and industrial activities in the reporting area excluding the food sector.
Non-point source (NPS) pollution is water pollution affecting a water body from diffuse sources, such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea. Nonpoint source pollution can be contrasted with point source pollution, where discharges occur to a body of water at a single location, such as discharges from a chemical factory, urban runoff from a roadway storm drain, or from ships at sea.
NPS may derive from many different sources with no specific solution to rectify the problem, making it difficult to regulate. It is the leading cause of water pollution in the United States today, with polluted runoff from agriculture the primary cause.
Contaminated stormwater washed off of parking lots, roads and highways, and lawns (often containing fertilizers and pesticides) is called urban runoff. This runoff is often classified as a type of NPS pollution. Some people may also consider it a point source because many times it is channeled into municipal storm drain systems and discharged through pipes to nearbysurface waters. However, not all urban runoff flows through storm drain systems before entering waterbodies. Some may flow directly into waterbodies, especially in developing and suburban areas. Also, unlike other types of point sources, such as industrial discharge, wastewater plants and other operations, pollution in urban runoff cannot be attributed to one activity or even group of activities. Therefore, because it is not caused by an easily identified and regulated activity, urban runoff pollution sources are also often treated as true nonpoint sources as municipalities work to abate them.
Principal types of nonpoint source pollution
Sediment (loose soil) includes silt (fine particles) and suspended solids (larger particles). Sediment may enter surface waters from eroding stream banks, and from surface runoff due to improper plant cover on urban and rural land Sediment creates turbidity (cloudiness) in water bodies, reducing the amount of light reaching lower depths, which can inhibit growth of submerged aquatic plants and consequently affect species which are dependent on them, such as fish and shellfish. High turbidity levels also inhibit drinking water purification systems. (Sediment can also be discharged from improperly managed construction sites, although these are point sources, which can be managed with erosion controls and sediment controls.)
Phosphorus is a nutrient that occurs in many forms that are bioavailable. It is a main ingredient in many fertilizers used for agriculture as well as on residential and commercial properties, and may become a limiting nutrient in freshwater systems. Excess amounts of phosphorus in these systems lead to algae blooms and consequently hypoxia. This is also known as eutrophication. Phosphorus is most often transported to water bodies via soil erosion forms of phosphorus tend to be adsorbed to soil particles.
Nitrogen is the other key ingredient in fertilizers, and it becomes a pollutant in saltwater systems where nitrogen is a limiting nutrient. Excess amounts of bioavailable nitrogen in these systems lead to a bloom of algae and diatoms. When the excessively large population of autotrophs reach the end of their life cycles, the process of decomposition consumes oxygen. The result is very suppressed levels of dissolved oxygen in the water, otherwise known as hypoxia.
Nitrogen is most often transported by water as nitrate (NO3). The nitrogen is usually added to a watershed as organic-N or ammonia (NH3), so nitrogen stays attached to the soil until oxidation converts it into nitrate. Since the nitrate is generally already incorporated into the soil, the water traveling through the soil (i.e., interflow and tile drainage) is the most likely to transport it, rather than surface runoff.
The moment that pollutants in soils become dissolved in natural waters, their potential for transport is greatly magnified, as is the likelihood that people will ingest them. The primary health risk from many hazardous waste sites, dumps, septic tanks, factory outflows, and other pollution sources is the possibility that pollutants will be dissolved into groundwaters or surface waters, then ultimately reach drinking water. Pollutants of concern include industrial solvents such as perchlorethlyene (PCE); trichlorethylene (TCE); motor fuel components such as benzene, toluene, ethylbenzene, and xylene, (collectively termed BTEX); and inorganic contaminants such as lead, chromate, arsenic, and nitrate. Just as each contaminant tends to affect specific organs in the human body depending on its chemistry, the behavior of contaminants in groundwaters and surface waters likewise varies from contaminant to contaminant. Rarely do chemicals behave identically in natural waters; typically there is at least one natural reaction that causes the bioavailability of a given contaminant to decrease, or attenuate, over time. These attenuation reactions include the following. Contaminant attenuation can be split into two components. Organic contaminants are made up of electron-rich molecules containing linked carbon atoms. Soil microorganisms can derive energy by using oxygen, sulfate, nitrate, or ferrous iron to oxidize and break these chains down into carbon dioxide plus water. Often this breakdown is more rapid than engineered remediation. Rapid microbial attenuation is often observed for fuel hydrocarbons such as are found beneath leaking underground fuel tanks. Attenuation tends to be most rapid under oxidizing (aerobic ) conditions that often prevail in loose soils. In oxygen-poor (anaerobic ) waters, attenuation tends to be slower. PCE and TCE are two of the most common contaminants at hazardous waste sites. They are quite toxic and also tend to resist chemical attenuation. Microorganisms are only able to rapidly attenuate them by first reducing them under anaerobic conditions, and then oxidizing them under aerobic conditions. Obviously the potential for PCE or TCE attenuation hinges upon the chemical condition of the aquifer or soil. Chemical attenuation of inorganic contaminants such as lead, chromate, nitrate, and arsenic often involves sorption onto mineral surfaces. Microorganisms generally cannot break down such contaminants into less toxic compounds except in a few cases. Most notably, microorganisms are able to reduce oxidized (and toxic) chromate to insoluble and less toxic trivalent chromium. Likewise, microorganisms can convert nitrate to ammonia and/or nitrogen gas. Most other inorganic contaminants must be sorbed to mineral surfaces to be attenuated. Soil and aquifer solids tend to be negatively charged because of broken or unsatisfied bonds that exist at their surfaces. This negative charge that exists at mineral surfaces pulls oppositely charged cations from solution. Many dissolved metals exist as positively charged cations in natural waters and are hence attracted to, and attenuated at, mineral surfaces. This is particularly true for such industrial metals as lead, cadmium, zinc, and nickel. It is also true for such important radionuclides that are present in radioactive waste as 90Sr, 137Cs, and isotopes of Pu (plutonium) and U (uranium). Chromate and arsenate sorb appreciably to many soil minerals despite the overall negative charge of both partners. Inorganic contaminants that initially sorb onto mineral surfaces from a contaminant-rich solution might in theory "desorb" back into contaminantpoor waters recharging a contaminated aquifer after the contaminant source has been removed. In fact, numerous field observations suggest that many sorbed contaminants become permanently sequestered after prolonged interaction with mineral surfaces. In other words, sorbed contaminants are taken up into mineral lattices (structures) where they are no longer bioavailable. Mineral uptake also makes the complete engineered removal of contaminants from soils and aquifers nearly impossible. In effect, the crystal lattices must be destroyed to remove the bound contaminants. Pollutant attenuation is most commonly taken advantage of in the treatment of sewage; that is, oxidation of organic matter is hastened by mixing on-site or by discharging into surface waters that have sufficient capacity to rapidly attenuate the imposed pollutant load. Increasingly, pollutant attenuation, or equivalently "monitored natural attenuation" or MNA, is being used as a component of hazardous waste site cleanups. Specifically, MNA is relied upon to remove contaminants from groundwaters, in parallel to and, after active remediation has ceased. Bioremediation of contaminated sites typically involves the engineered acceleration of natural organic activity that leads to the breakdown of organic contaminantsâ€”most commonly spilled fuels and solventsâ€”ultimately to carbon dioxide. Less common is the introduction of new organisms, themselves, to contaminated sites. Natural soil organic activity tends to be sufficiently pervasive that, given the appropriate nutrients, breakdown of contaminants can be achieved by native populations of microorganisms. Nutrient additions may include oxygen, a carbon substrate such as molasses, and/or hydrogen. It must be noted that not all contaminants attenuate rapidly enough to prevent potential impacts on human health. Instead, knowledge of attenuation rates and capacities is critical to the successful implementation of pollutant attenuation in either realm. Each area remains the subject of intense investigation by chemists, biologists, geochemists, engineers, and other scientists. see also Fresh Water, Natural Composition of; Fresh Water, Physics and Chemistry of; Groundwater; Modeling Groundwater Flow and Transport; Modeling Stream Flow and Quality; Pollution of Groundwater; Pollution of Lakes and Streams; Radioactive Chemicals; Septic System Impacts; Wastewater Treatment and Management. Patrick V. Brady Brady, Patrick V., Michael V. Brady, and David J. Borns. Natural Attenuation: CERCLA, RBCAs, and the Future of Environmental Remediation. Boca Raton, FL: Lewis Publishers, 1997. Rice, David W. et al. "Recommendations to Improve the Cleanup Process for California's Leaking Underground Fuel Tanks." In Lawrence Livermore National Laboratory Report. Lawrence Livermore National Laboratory, CA: 1995.
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Answers:This essay may give you some ideas.~ Air pollution Introduction With the great concern surrounding the destruction of the earth s atmosphere due to air pollution, the immediate and direct harm caused to the human body is often over shadowed. While many are aware that our careless use of hazardous chemicals and fossil fuels may leave the planet uninhabitable in the future, most over look the fact that they are also cause real damage to our bodies at this moment. Such pollutants cause damage to our respiratory system, leading to the fluctuation of the life span of an individual depending on a number of conditions. Amongst these conditions are the individuals specific geographic location, age, and life style. This paper is structured as a series of relevant questions and answers to report on the description of these pollutants there affects on our bodies. What are the pollutants? And how do they affect our bodies? In order to understand how air pollution affects our body, you must under stand exactly what this pollution is. The pollutants that harm our respiratory system are known as particulates. Particulates are the small solid particles that you can see through a ray of sunlight. They are products of incomplete combustion in engines (example: automobile engines), road dust, and wood smoke. Billions of tons of coal and oil are consumed around the world every year. When these fuels burn they produce smoke and other by-products into the atmosphere. Although wind and rain occasionally wash away the smoke given off by power plants and automobiles, much still remains. Particulate matter (soot, ash, and other solids), usually consist of unburned hydrocarbons, carbon monoxide, sulfur dioxide, various nitrogen oxides, ozone, and lead. These compounds undergo a series of chemical reactions in the presence of sunlight, the result is smog (a term used to describe a noxious mixture of fog and smoke) The smog in this photograph of Beijing, China is so dense that you can barely see the mountains The process by which these pollutants harm our bodies begins by simply taking a breath. Particulates are present every where, in some areas they are as dense as 100,000 per milliliter of air. The damage begins when the particulates are inhaled into the small air sacs of our lungs called alveoli. With densities such as 100,000 per milliliter a single alveolus may receive 1,500 particulates per day. These particulates cause the inflammation of the alveoli. The inflammation causes the body to produce agents in the blood that in crease clotting ability, which leads to the decreased functionality of the cardiovascular system, resulting in diseases and increased mortality. In the blood, carbon monoxide interferes with the supply of oxygen to all tissues and organs, including the brain and heart. Particulates accumulate on the mucous linings of the airways and lungs and impair their functioning. Continued exposure to particulates damages the lungs and increases an individual's chances of developing such conditions as chronic bronchitis and emphysema. Inside the alveoli of the lungs, particulate air pollution irritates and inflames them. While you may see pollutants such as particulates, other harmful ones are not visible. Amongst the most dangerous to our health are Carbon Monoxide, Nitrogen Oxides, Sulfur dioxide, and Ozone. If you have ever been in an enclosed parking garage or a tunnel and felt dizzy or light-headed then you have felt the effect of carbon monoxide(CO). This odorless, colorless, but poisonous gas is produced by the incomplete burning of fossil fuels, like gasoline or diesel fuel. Carbon Monoxide comes from cars, trucks, gas furnaces and stoves, and some industrial processes. CO is also a toxin in cigarettes. Carbon Monoxide combines with hemoglobin in the red blood cells, so body cells and tissues cannot get the oxygen they need. Carbon Monoxide attacks the immune system, especially affecting anyone with heart disease, anemia, and emphysema and other lung diseases. Even when at low concentrations CO affects mental function, vision, and alertness. Nitrogen Oxide is another pollutant that has been nicknamed a jet-age pollutant because it is only apparent in highly advanced countries. Sources of this are fuel plant, cars, and trucks. At lower concentrations nitrogen oxides are a light brown gas. In high concentrations they are major sources of haze and smog. They also combine with other compounds to help form ozone. Nitrogen Oxides cause eye and lung irritation, and lowers the resistance to respiratory illness, such as chest colds, bronchitis, and influenza. For children and people with asthma, this gas is can cause death. Nitrogen Oxides maybe the most dangerous of these pollutants because it also makes nitric acid, when combine with water in rain, snow, fog, or mist. This then becomes the harmful acid rain. Sulfur Dioxide is a heavy, smelly, colorless gas which comes from industrial plants, petroleum refineries, paper
Answers:The correct answer is NOx. Oxides of sulfur do not assist in formation of ozone.
Answers:Here are the six common pollutants according to EPA (US Environmental Protection Agency): 1. Ozone (O3) is a gas composed of three oxygen atoms. It is not usually emitted directly into the air, but at ground-level is created by a chemical reaction between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. Ozone has the same chemical structure whether it occurs miles above the earth or at ground-level and can be "good" or "bad," depending on its location in the atmosphere. In the earth's lower atmosphere, ground-level ozone is considered "bad." Motor vehicle exhaust and industrial emissions, gasoline vapors, and chemical solvents as well as natural sources emit NOx and VOC that help form ozone. Ground-level ozone is the primary constituent of smog. Sunlight and hot weather cause ground-level ozone to form in harmful concentrations in the air. As a result, it is known as a summertime air pollutant. Many urban areas tend to have high levels of "bad" ozone, but even rural areas are also subject to increased ozone levels because wind carries ozone and pollutants that form it hundreds of miles away from their original sources. 2. Particulate matter also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets. Particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles. 3. Carbon monoxide, or CO,is a colorless, odorless gas that is formed when carbon in fuel is not burned completely. It is a component of motor vehicle exhaust, which contributes about 56 percent of all CO emissions nationwide. Other non-road engines and vehicles (such as construction equipment and boats) contribute about 22 percent of all CO emissions nationwide. Higher levels of CO generally occur in areas with heavy traffic congestion. In cities, 85 to 95 percent of all CO emissions may come from motor vehicle exhaust. Other sources of CO emissions include industrial processes (such as metals processing and chemical manufacturing), residential wood burning, and natural sources such as forest fires. Woodstoves, gas stoves, cigarette smoke, and unvented gas and kerosene space heaters are sources of CO indoors. The highest levels of CO in the outside air typically occur during the colder months of the year when inversion conditions are more frequent. The air pollution becomes trapped near the ground beneath a layer of warm air. 4. Nitrogen dioxide (NO2) is one of a group of highly reactive gasses known as "oxides of nitrogen," or "nitrogen oxides (NOx)." Other nitrogen oxides include nitrous acid and nitric acid. While EPA s National Ambient Air Quality Standard covers this entire group of NOx, NO2 is the component of greatest interest and the indicator for the larger group of nitrogen oxides. NO2 forms quickly from emissions from cars, trucks and buses, power plants, and off-road equipment. In addition to contributing to the formation of ground-level ozone, and fine particle pollution, NO2 is linked with a number of adverse effects on the respiratory system. 5. Sulfur dioxide (SO2) is one of a group of highly reactive gasses known as oxides of sulfur. The largest sources of SO2 emissions are from fossil fuel combustion at power plants (73%) and other industrial facilities (20%). Smaller sources of SO2 emissions include industrial processes such as extracting metal from ore, and the burning of high sulfur containing fuels by locomotives, large ships, and non-road equipment. SO2 is linked with a number of adverse effects on the respiratory system. 6. Lead (Pb) is a metal found naturally in the environment as well as in manufactured products. The major sources of lead emissions have historically been motor vehicles (such as cars and trucks) and industrial sources. As a result of EPA's regulatory efforts to remove lead from gasoline, emissions of lead from the transportation sector dramatically declined by 95 percent between 1980 and 1999, and levels of lead in the air decreased by 94 percent between 1980 and 1999. Today, the highest levels of lead in air are usually found near lead smelters. Other stationary sources are waste incinerators, utilities, and lead-acid battery manufacturers.
Answers:An air pollutant is known as a substance in the air that can cause harm to humans and the environment. Pollutants can be in the form of solid particles, liquid droplets, or gases. In addition, they may be natural or man-made. Pollutants can be classified as either primary or secondary. Usually, primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide 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 primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone - one of the many secondary pollutants that make up photochemical smog. Note that some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants. About 4 percent of deaths in the United States can be attributed to air pollution, according to the Environmental Science Engineering Program at the Harvard School of Public Health. Major primary pollutants produced by human activity include: * Sulfur oxides (SOx) - especially sulfur dioxide, a chemical compound with the formula SO2. SO2 is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain. This is one of the causes for concern over the environmental impact of the use of these fuels as power sources. * Nitrogen oxides (NOx) - especially nitrogen dioxide are emitted from high temperature combustion. Can be seen as the brown haze dome above or plume downwind of cities.Nitrogen dioxide is the chemical compound with the formula NO2. It is one of the several nitrogen oxides. This reddish-brown toxic gas has a characteristic sharp, biting odor. NO2 is one of the most prominent air pollutants. * Carbon monoxide - is a colourless, odourless, non-irritating but very poisonous gas. It is a product by incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide. * Carbon dioxide (CO2) - a greenhouse gas emitted from combustion but is also a gas vital to living organisms. It is a natural gas in the atmosphere. * Volatile organic compounds - VOCs are an important outdoor air pollutant. In this field they are often divided into the separate categories of methane (CH4) and non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which contributes to enhanced global warming. Other hydrocarbon VOCs are also significant greenhouse gases via their role in creating ozone and in prolonging the life of methane in the atmosphere, although the effect varies depending on local air quality. Within the NMVOCs, the aromatic compounds benzene, toluene and xylene are suspected carcinogens and may lead to leukemia through prolonged exposure. 1,3-butadiene is another dangerous compound 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. In contrast, aerosol refers to particles and the gas together. Sources of particulate matter can be man made or natural. Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes also generate significant amounts of aerosols. Averaged over the globe, anthropogenic aerosols those made by human activities currently account for about 10 percent of the total amount of aerosols in our atmosphere. Increased levels of fine particles in the air are linked to health hazards such as heart disease, altered lung function and lung cancer. * Toxic metals, such as lead, cadmium and copper. * Chlorofluorocarbons (CFCs) - harmful to the ozone layer emitted from products currently banned from use. * Ammonia (NH3) - emitted from agricultural processes. Ammonia is a compound with the formula NH3. It is normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to foodstuffs and fertilizers. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceuticals. Although in wide use, ammonia is both caustic and hazardous. * Odors - such as from garbage, sewage, and industrial processes * Radioactive pollutants - produced by nuclear explosions, war explosives, and natural processes such as the radioactive decay of radon. Secondary pollutants include: * Particulate matter