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What Is Air Pollution?
Clean air is essential for living things but unfortunately, much of the air we breathe in is in fact not clean.
Air pollution is defined as the condition in which air contains a high concentration of certain chemicals that may impact living things negatively such as human and animals and damage natural environment or built environment.
What Causes Air Pollution?
Air pollution is caused by solid particles and poisonous gases in the air.
These substances are called air pollutants which include carbon monoxide,oxides of nitrogen and sulfur dioxide.
This video shows the effect of air pollution in most polluted place on earth, the coal-mining town of Linfen in Shanxi Province, China, where kids play in dirty rivers and the sun sets early behind a thick curtain of smog.
4 Facts You Didn't Know About Air Pollution
Major pollutants
1. Particulate Matter (PM)
Particulate matter is the mixture of airborne particles (liquid droplets and solid particles), both organic and inorganic
all of which is lesser than 10 micrometer in size and hazardous. They differ in origin, chemical composition
and size. How big are they?
An example where a single human hair is at least 70 micrometer in diameter, which which makes it 30 times larger than the largest fine particle.
Some particles such as dirt, soot, dust or smoke are large/dark enough to be seen with naked eye while others are too small and can only be detected using an electron microscope.
Why does the particle size matter
★The size of the particles determine how they are transported in the air and how they can be removed. This property also shows
the severeness of health effects. Particulate matter can be divided into two types —Inhalable coarse particles and fine particles
Inhalable coarse particles are smaller than 10 micrometers but bigger than 2.5 micrometers (2.5-10 μm) or PM10
Fine particles are smaller than 2.5 micrometers (<2.5 μm) or PM2.5
(a) key sources
Identifying the origins
★Inhalable coarse particles (primary particles) are those directly emitted from a source such as construction
sites, smokestacks, fields, unpaved roads and fires. These anthropogenic sources (caused by humans) increases
airborne particulate concentrations in many locations. Also not to forget natural sources like volcanic eruptions that too releases particulate matter in the air. Inhalable coarse particles or primary particles are more direct than fine particles.
★Fine particles (secondary particles) are indirectly formed, when gaseous pollutants emitted from power plants, industries, automobiles (where fuel is burned in) and forest fires form in complicated reactions in the atmosphere to become particulate matter. The difference between PM10 and PM2.5 is that the finer particles are definitely smaller and contain more toxic and carcinogenic (cancer causing) compounds.
(b) effects on health & environment
The severeness of the health effects are ruled by size, concentration and composition
Aesthetic & Environmental Damage
★These particles disperse in the air and travel over great distances, meaning they do not always land near the place of source. They are carried over by wind and settles onto the ground or water.
The effects: increasing acidity in lakes and streams, altering nutrient balance in soil, coastal waters and large river basins, damages crops, and as well as affects the diversity of ecosystems.
Picture of one of Dallol's acidic lakes, polluted from deposits of particulate matter (iron, sulfur) location: Ethiopia
★Particles in the air can also cause stains and damage to materials, including to buildings and culturally important objects like statues, monuments. Not only that but fine particles (PM2.5) is also the main cause of reduced visibility (haze) in most parts of the world, including treasured national parks and wilderness areas.
Stone fountain in Rome, Italy, showing damage caused by weathering
Getting into the body
★Upon inhalation, the particles enter through our airway and travel into our respiratory system. The particles can stick to the sides of airway or travel deeper into the lungs. The smaller the particles, the further it can travel. The farther the particles travel, the worse the effect.
Exposure to these particles causes specifically respiratory problems, including these variety:
premature death in people with heart or lung disease,
nonfatal heart attacks,
irregular heartbeat,
aggravated asthma,
decreased lung function, and
increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing.
People who are more susceptible at higher risk of the health effects are elderly people with respiratory defects,
pregnant women, people with high labour activity and especially children as they have higher physical activity
and higher ventilation. Nevertheless, when the levels of particulate matter in the air is high, the entire population
and all individuals are at risk. Healthy people may even experience temporary symptoms from exposure of elevated levels.
(c) solution
Particulate matter in the air contributes significantly to air pollution, and whereby this is concerned it is imperative to control emissions in the air. From what we've learnt from the direct sources of emissions, we understand that industry, agriculture, automobiles and heating are much responsible for this public health issue therefore these suggested measures are things we can do to reduce impact on air quality on a worldwide/regional/ or even individual level.
control vehicle flow: developing highway measures (such as regulating city centre vehicle access, reducing traffic lanes and parking) and other restrictive urban toll installations
encourage shift towards more sustainable type of transport: instead of diesel engines, use combustion engine cars that have advanced hybrid technology to enable switch to electric mode when in polluted areas. Or better still, take the public transport and carpooling.
set emission standards: control emissions by industrial facilities emitting harmful toxins that reduce visibility, and fine particles.
Invent a technical approach: offer control devices such as particle filters or (SCR) selective catalytic reduction systems to impede output of particulate matter into the air
Avoid unhealthy exposure: Reduce smoking inside and use of particle sources such as candles and wood-burning stoves. When air quality is poor, avoid being active outdoors and substitute physical outdoor activity to less exertion.
2. Carbon Monoxide (CO)
Carbon Monoxide is a poisonous gas that is colourless, odourless and tasteless.
It is slightly denser than air and it is produced by the incomplete combustion of carbon-containing fuels.
These three graphs prove that most of the carbon monoxide emission is from transportation
Identifying the origins
Graph of Carbon Monoxide Emissions between 1970 and 2002 from U.S Environmental Protection Agency Pie chart of Sources of Carbon Monoxide Emissions
This graph and pie chart proves that most of the carbon monoxide emissions come from transportation.
Carbon monoxide is a component of motor vehicle exhaust that contributes about 55% of all CO emissions nationwide. Other non-road engines and vehicles contribute about 22% of all CO emissions nationwide. Higher levels of CO generally occur in areas with heavy traffic congestion. In cities, 85% to 95% of all CO emissions may come from motor vehicle exhaust.
Other sources of CO emissions include industrial processes, residential wood burning, as well as natural sources such as forest fires. Wood stoves, gas stoves, cigarette smoke, and unvented gas and kerosene space heaters are sources of CO indoors.
Forest fire smog blankets Singapore in 2014
Singapore and neighbouring Malaysia are smothered annually by smog from forest fires in Indonesia [AFP]
★On September 14 2014, air pollution in Singapore rose to unhealthy levels after clouds of smog from fires raging across rainforests in the Indonesian island of Sumatra covered the city-state's skyline.
★PSI reached a high of 111 at 7:00 am (2300 GMT) on Monday before easing to 80 a few hours later. A reading between 101-200 is considered "unhealthy". Therefore, people with respiratory or heart problem are advised to reduce physical exertion and outdoor activity. White smog shrouded Singapore's skyline, with smoke wafting into the business district.
Aesthetic & Environmental Damage
Carbon monoxide is different as it stays in the atmosphere for a period of time and moves along far distances. Also, it contributes to the formation of smog, ground-level ozone, which can cause serious respiratory problems. It is not uniformly distributed around the Earth.
This shows how acid rain had damaged The Leshan Giant Buddha, that was built during the Tang Dynasty (618-907).
★ reducing oxygen delivery to the body's organs (eg. heart and brain) and tissues.
★ cause headache, dizziness, vomiting, and nausea. If CO levels are high enough, you may become unconscious or die.
★Exposure of carbon monoxide to people with heart diseases is even more serious for them because they already have a reduced capacity for pumping oxygenated blood to the heart.
★In fact, high levels of CO can also affect healthy people. People who breathe high levels of CO can develop vision problems, reduced ability to work or learn, reduced manual dexterity, and difficulty performing complicated tasks.
Avoid excessive usage of lawn mowers and other devices with small petrol engines.
Make sure that our vehicles are regularly serviced, ensuring they are running as efficiently as possible.
encourage using bicycle or walking as a form of transport.
use small cars instead of big cars as small cars are more fuel efficient.
use Green cars because they are usually much more environmentally friendly and more properties mentioned below:
ØNot only better for the environment, it will also save money.
ØGreen cars are affordable and cost the same as conventional cars.
ØThere are number of Green cars which are Hybrid cars, Electric cars, Hydrogen cars and Solar cars.
3. Sulfur Dioxide (SO2)
Identifying the origins
Sulfur Dioxide mainly comes from volcanic eruption. It also comes from the combustion of fossil fuels such as coal, petroleum & natural gas.
An example to show sulfur dioxide is not uniformly distributed
Getting into the body
★Immediate symptom: eye & lungs irritation, which in turns lead to breathing difficulty. Excess sulfur dioxide will lead to bronchitis — inflammation of the lungs.
★Long term effect: kidney failure and cancer
Aesthetic & Environmental Damage
Sulfur dioxide will also affect our environment negatively, by causing acid rain, which ultimately destroys buildings, aquatic life & plants.
shift to lower sulfur fuels
shift fuel consumption from electricity to pipeline grade gas made from coal to solar energy
removal of sulfur from coal before combustion, or of the sulfur oxide after combustion
**Another alternative is usingFlue Gas Desulfurisation [FGD]
Definition of Flue Gas: waste gases produced when fossil fuels undergo combustion
Desulfurisation: process of removing sulfur dioxide from Flue Gas
4. Ozone Depletion
What is Ozone Layer?
Ozone layer is the layer in the Earth's stratosphere. Ozone layers absorb most of the ultraviolet(UV) radiation reaching the Earth from the Sun.
What is Ozone Depletion?
Ozone Depletion is the wearing out of the amount of ozone in the stratosphere (second major atmospheric above the troposphere - lowest major atmospheric layer).
Pollution has many types and causes. As for Ozone Depletion, it has put together as one major human activity.
How did Ozone Depletion occur?
Ozone Depletion starts when chlorofluorocarbons (CFCs) such as foams, air conditioner and refrigerator gets into the stratosphere. Although these materials are denser than air, 2-5 years ahead, they will be carried by the wind into the stratosphere . When the CFCs break down due to it UV radiation, it release chlorine atoms. A chemical cycle that destroys the good ozone begins when chlorine atoms react with ozone.
Ozone destruction caused by chlorine
Most of the sun's potentially harmful shortwave UV radiation are filter out by the stratospheric ozone. More UV rays will reach the earth if the ozone continue to deplete. There will be serious impacts on human beings, animals and plants if they are exposed to higher amount of UV radiation such as skin cancer, cataract, weakening of human immune system, reduced growth especially for seedlings photosynthesis and flowering for plant. Animals can also get cataract and skin cancer. As for the marine life, plankton are threatened by increased UV radiation. Fresh and saltwater food chains may be disrupted by the drop in the amount of plankton. Lost of biodiversity in our oceans, rivers and lakes could reduce fish yields for commercials and sport fisheries. Last but not least , materials such as woods, plastics, rubber, fabrics and many other construction materials are degraded by UV radiation.
How to monitor air pollution
Is it only CFCs that contribute to Ozone Depletion?
No. There are also other Ozone Depleting Substances (ODS) such as methyl bromide used in pesticides, halons used in fire extinguisher etc. Other chemicals that naturally destroy ozones are Noy, Hox, Clx which belongs to the Nitrogen, Hydrogen and Chlorine families.
What can be done?
Ozone is natural gas and is naturally replenished over time. Surely there should not be a problem if we can do something to balance the natural production with its depletion. Unfortunately, it does not quite work that way. The only way is to remove the excess chlorine and bromine from the stratosphere. And to do so, we must stop making CFCs and several other chemicals. This is too obviously not enough, but at least its a good starting point.
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