This is the fourth slideshow in a series for Unit 4 VCE Environmental Science. It discusses the factors contributing to air pollution, the sources and sinks and the human and environmental health effects.
VCE Environmental Science: Unit 4 Area of Study 1: Pollution
Air pollution is the “introduction of chemicals, particulate matter or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural or built environment, into the atmosphere.” There is great concern over deteriorating air quality as it can contribute to many health problems in our community, especially for the very young, the elderly and those who already have respiratory problems.
1. List in the chat window all the possiblesources of air pollution in your local area.
A. Industrial sourcesB. Electricity generationC. Transport emissionsD. All of the above
Cancers and premature death can also be attributed to poor air quality. Air pollution not only has a real health cost, it also has an economic and environmental cost. Economic effects include the increased use of the health system and reduced activity of affected people, while environmental effects include damage to plants, animals and man-made structures, such as buildings and monuments.
Weather conditions can affect the amount of pollution in the air: Wind Temperature Airpressure Cloud cover Fog, dew and frost Precipitation (rain, snow, hail)
1. I think air pollution is getting worse 2. Photochemical smog occurs where there is lots of sunlight and high temps. 3. The main component of smog is ozone 4. Jogging on high smog days harms your health 5. Wood-heaters add fine particles to the air 6. Air quality could be improved if more people used public transport.
Larger particles in the air are readily washed out in light rain. Fine and ultra fine particles require moderate to heavy rain to be washed to the ground. It should be noted that pollutant gases are generally not affected by light rain. However, nitrogen dioxide dissolves in water and is washed to the ground. Rainfall measurements will also be helpful in interpreting other air pollution measurements. For example, if there was exposed soil, windy days would cause much of this to be blown into the atmosphere and raise particulate (PM) readings. However, if there had been rain in the previous 48 hours, the soil may well stay put and hence, particulate readings would be lower.
Name as many as you can think of in the chat window.
Carbon monoxide and CO2 Nitrogen oxides (esp. NO2) CFC’s Volatile Organic Compounds Ammonia Odours Particulate matter Pollen, dust-mites and other allergens Radioactive compounds Oxides of Sulphur (esp. SO2)
It has been estimated that there were more dioxins released into the atmosphere from the fireworks in Sydney for the commencement of the year 2000 than was released for the entire year from industrial sources. If this is so, why is there such a focus on industry, rather than other sources for controlling dioxins?
CO 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.
CO2 is a colourless, odourless, non-toxic greenhouse gas associated with ocean acidification, emitted from sources such as combustion of fossil fuels, cement production and respiration.
NOx, especially nitrogen dioxide, are emitted from high temperature combustion. They can be seen as the brown haze dome above or plume downwind of cities. Nitrogen dioxide is a reddish- brown toxic gas with a characteristic sharp, biting odour. NO2 is one of the most prominent air pollutants, causing respiratory illnesses and reducing ventilation (air getting to the lungs), especially in young children, the elderly and those with respiratory illnesses.
NO2 is also a precursor to summer smog, which is fast becoming a major problem in our cities. The NO2 in the atmosphere reacts with oxygen (O2) in the air when it is sunny and the temperatures are high to form ozone (O3) — the major component of summer smog. Summer smog causes eye, nose and throat irritation, damages the respiratory tract and increases our sensitivity to allergens. These oxides of nitrogen are removed from the air by rain, by plants and by contact with surfaces.
Chloroflourocarbons (CFCs) are harmful to the ozone layer They are emitted from old aerosol cans and refrigeration units. Banned from use since 1989.
VOCs include methane and other hydrocarbons, such as benzene, toluene and xylene. VOCs are significant greenhouse gases via their role in creating ozone and in prolonging the life of methane in the atmosphere. VOC’s are suspected carcinogens and may lead to leukemia through prolonged exposure.
Ammonia is emitted from agricultural processes and is normally encountered as a gas with a characteristic pungent odour. 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
Odours are also classified as air pollutants and can originate from: Garbage and landfills Sewage and treatment plants Industrial processes (milk and cheese processing for example) Dairies, sheep-yards, saleyards, zoos and abattoirs
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. “Dirty Little Secrets” from ABC Catalyst is about the effects of PM on human health. http://www.abc.net.au/catalyst/stori es/s1630007.htm
Indoor particulate matter can include dust, smoke, pollen, animal dander, tobacco smoke, particles generated from combustion appliances such as cooking stoves, and particles associated with tiny organisms such as dust mites, moulds, bacteria, and viruses. Outdoors, the anthropogenic sources of particulate matter can be vehicle exhausts, industrial processes, wood heaters, fuel- reduction burning and power generation.
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.
The increased rates of allergy and asthma in city environments and in those living close to highways has drawn attention to the role of outdoor pollution. Common air pollutants, such as ozone, sulfur dioxide, and nitrogen dioxide probably act more as irritants than as promoters of sensitization. These pollutants have been shown to be hazardous to adults and children with asthma. Recent studies suggest that prematurely born children are more sensitive to the respiratory effects of outdoor pollution. There may also be an association with diesel exhaust particles and the worldwide increase in respiratory allergies. Diesel exhaust has been shown to enhance the ability to make the allergy antibody, IgE, in response to exposure to allergens.
Indoor air pollution is among thetop five environmental healthrisks.* Gaseous pollutants can bereleased from furnishings and fromadhesives, paints, varnishes,cleaning products and pesticides,all of which contribute to poorindoor air quality. Pollen, dust-mitefaeces, skin flakes, pet dander,tobacco smoke and otherallergens can be reduced byregular cleaning and adequateventilation. *http://www.epa.gov/iaq/pubs/airclean.html
Pollen is in the air seasonally,with the amount varying fromone area to another,depending on the types of windpollinating plants in the regionand the weather conditions.For some people the amount ofpollen in the air has a directeffect upon their health.Airborne pollen on its own, or incombination with fine particlesin the air, can influence theincidence and severity ofasthma and hayfever in thecommunity.
During and after rain (often thunderstorms) some grains of pollen burst, releasing the allergen containing starch granules. In Melbourne after rain, air samples have been shown to contain up to 50 times more starch granules than air sampled on a sunny day during the grass pollen season. The starch granules are small enough to be breathed in and can enter the bronchi (tubes to the lungs), where they may trigger allergic asthma.
Produced by nuclear explosions and damaged nuclear power plants, war explosives and natural processes such as the radioactive decay of radon.
Oxides of Sulphur, especially sulphur dioxide, a chemical compound with the formula SO2 are common pollutants of the air. SO2 is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulphur compounds, their combustion generates sulphfur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain.
Sulphur dioxide (SO2) is a colourless gas that is similar in smell to a matchstick being struck. As its name suggests it is a compound consisting of sulphur and oxygen, and has both natural and anthropogenic or man-made sources. It has significant health and environmental effects, including the formation of acid rain and smog and influences global warming.
Sulphur dioxide consists of one atom of sulphur bonded to two atoms of oxygen. It is a strong, acrid smelling, non-flammable gas. It reacts in the atmosphere to form sulphur trioxide, and dissolves readily in water vapour, forming sulphuric acid. It can also attach to dust and soot particles in the atmosphere to form particulates. From these reactions, a wide range of effects are possible, including the formation of pollutants that influence both human health and environmental processes.
Sulphur dioxide is formed through a number of pathways, including the burning of sulphur in the presence of oxygen and the oxidation of hydrogen sulphide, commonly emitted from wetlands. Natural sources include volcanoes, forest- fires, oceans and decaying plant matter. These outweigh anthropogenic sources, with volcanic activity producing about 20% of the global total. In Australia, the two main anthropogenic sources are power stations and metal manufacturing, while smaller sources include home-heating, chemical production and transportation emissions.
Sulphur dioxide is a naturally occurring compound with a number of sinks or areas that can absorb excess amounts thus reducing its abundance in the environment, such as the oceans, wetlands and lakes.
This phenomenon results when sulphur dioxide dissolves in moisture in the air, forming sulphur acids, which eventually fall to the surface of the earth as acid rain. Acid rain directly attacks the protective coating of plants, acidifies lakes and soils which may result in the formation of substances that are toxic to plants and animals.
This has been a major problem in northern USA, Canada and Scandinavia, where forests have been severely damaged, but fortunately regulations are improving emission standards, and reducing the incidence of acid rain. Coal mined in Australia is typically low in sulphur; therefore emissions are usually not a problem. We also have large sinks (oceans) in the southern hemisphere which assists to reduce the effects.
In addition to damaging living organisms, acid rain can have a severe effect on buildings made of marble or limestone. Commonly used in statues and older buildings, these materials slowly dissolve under acidic conditions leading to structural failure. This has been a significant problem in Europe with many old buildings made of marble and limestone.
The presence of high levels of sulphur dioxide has a negative effect on human health and society. Inhaled sulphur dioxide quickly dissolves with moisture on the lining of the lungs and nose, burning the mucous membranes. This is clear to anyone who accidentally inhales the smoke from a match being struck. Chronic - or long-term - exposure to high levels of SO2 leads to breathing problems and respiratory illnesses such as asthma, bronchitis as well as heart disease. Children tend to more vulnerable due to less developed lungs.