Air Pollution: Causes and Sources

Causes of Air Pollution

• Air pollution is the contamination of the atmosphere by wastes from sources like industrial burning and automobile exhausts.
• Air pollution can be solid, liquid, or gas.
• Most air pollution results from human activities.
• Some air pollution is natural.
• Natural sources of air pollution include dust, pollen, spores, and sulfur dioxide from volcanic eruptions.

Primary and Secondary Pollutants

• A primary pollutant is a pollutant put directly into the atmosphere by human or natural activity (ex: soot from smoke).
• A secondary pollutant is a pollutant that forms in the atmosphere by chemical reactions with primary air pollutants, natural components in the air, or both (ex: ground-level ozone).

Sources of Primary Pollutants

• Primary pollutant sources include household products and power plants.
• Motor vehicles are sources of primary pollutants like carbon monoxide, nitrogen oxide, sulfur dioxide, and volatile organic compounds (VOCs).
• Primary pollutants include carbon monoxide, nitrogen oxide, sulfur dioxide, and volatile organic compounds (VOC's).
• Vehicles and coal-burning power plants are major sources of nitrogen oxide emissions.
• Power plants, refineries, and metal smelters contribute much of the sulfur dioxide emissions.
• Vehicles and gas stations make up most of the human-made emissions of VOCs.
• Particulate matter can also pollute the air.
• Air particulate matter is divided into fine and coarse particles.
• Fine particles enter the air from fuel burned by vehicles and coal-burning power plants.
• Sources of coarse particles include cement plants, mining operations, incinerators, and wood-burning fireplaces, as well as fields and roads.

History of Air Pollution

• Air pollution is not a new phenomenon.
• In 1273 King Edward I ordered that burning a particularly dirty kind of coal called Sea-Coal was illegal.
• Air quality is much worse due to modern industrial societies burning large amounts of fossil fuels.
• Most air pollution in urban areas comes from vehicles and industry.

Motor Vehicle Emissions

• Almost 1/3 of air pollution comes from gasoline burned by vehicles.
• In 1998, Americans drove vehicles over 2.6 Trillion Miles.
• Over 90% of that mileage was driven by passenger vehicles.

Controlling Vehicle Emissions

• The Clean Air Act, passed in 1970 and strengthened in 1990, gives the EPA the authority to regulate vehicle emissions in the United States.
• The EPA required the gradual elimination of lead in gasoline, decreasing lead pollution by more than 90 percent.
• Catalytic converters, required in all automobiles, clean exhaust gases of pollutants.

California Zero-Emission Vehicle Program

• In 1990, the California Air Resources Board established the zero-emission vehicle (ZEV) program.
• Zero-emission vehicles have no tailpipe emissions, no emissions from gasoline, or emission-control systems that deteriorate over time.
• By 2016, 16% of all vehicles sold in California are required to be zero-emission vehicles, including SUVs and trucks.

Industrial Air Pollution

• Many industries and power plants that generate electricity burn fuel, usually fossil fuels.
• Burning fossil fuels releases quantities of sulfur dioxide and nitrogen oxide.
• Power plants that produce electricity emit at least two-thirds of all sulfur dioxide and more than one-third of all nitrogen oxides.
• Some industries also produce VOCs, which are chemical compounds that form toxic fumes.
• Examples of industries include dry cleaning, oil refineries, chemical manufacturing plants, furniture refinishers, and auto repair shops.

Regulating Air Pollution from Industry

• The Clean Air Act requires many industries to use scrubbers or other pollution-control devices.
• Scrubbers remove some of the harmful substances that would otherwise pollute the air.
• A scrubber is a machine that moves gases through a spray of water that dissolves many pollutants.
• Ammonia is a pollutant gas that can be removed using a scrubber.
• Electrostatic precipitators are machines used in cement factories and coal-burning power plants to remove dust particles from smokestacks.
• In an electrostatic precipitator, gas containing dust particles is blown through a chamber containing an electrical current.
• An electric charge is transferred to the dust particles, causing them to stick together and to the sides of the chamber.
• The clean gas is released from the chamber, and the concentrated dust particles can then be collected and removed.
• 20 Million Tons of ash generated by coal-burning power are removed by electrostatic precipitators.

Smog

• Smog is urban air pollution composed of a mixture of smoke and fog produced from industrial pollutants and burning fuels.
• Smog results from chemical reactions that involve sunlight, air, automobile exhaust, and ozone.

Temperature Inversions

• The circulation of air in the atmosphere usually keeps air pollution from reaching dangerous levels.
• During the day, the sun heats the surface of the Earth and the air near the Earth.
• A temperature inversion is when warm air traps cooler air near the Earth's surface.

Air Pollution - Effects on Health

• Air pollution can exacerbate existing diseases such as emphysema, heart disease, and lung cancer.
• Short-term effects of air pollution include headache, nausea, irritation to the eyes, nose, and throat, coughing, and tightness in the chest, as well as upper respiratory infections, such as bronchitis and pneumonia.
• Long-term effects on health that have been linked to air pollution include emphysema, lung cancer, and heart disease.

Indoor Air Pollution

• Major sources of pollution include plastics and industrial chemicals.
• These compounds can be found in carpets, building materials, paints, and furniture.
• Sick-building syndrome is a set of symptoms that can affect workers in airtight office buildings.
• Additional symptoms include headache, fatigue, eye irritation, and dizziness.
• Sick-building syndrome is believed to be caused by indoor air pollutants and is most common in hot places where buildings are tightly sealed to keep out the heat.
• Identifying and removing the sources of indoor air pollution is the most effective way to maintain good indoor air quality.
• Also, necessary for good air quality is proper Ventilation.

Radon Gas

• Radon gas is colorless, tasteless, odorless, and radioactive.
• Radon is one of the elements produced by the decay of uranium, a radioactive element that occurs naturally in the Earth's crust.
• Radon can seep through cracks and holes in foundations into homes, offices, and schools, where it adheres to dust particles.
• When people inhale the dust, radon enters their lungs and can destroy their genetic material in cells that line the air passages.
• Such damage can lead to cancer, especially among people who smoke.
• Radon is the second-leading cause of lung cancer in the United States.

Asbestos

• Asbestos is any of six silicate minerals that form bundles of minute fibers that are heat-resistant, flexible, and durable.
• Asbestos is primarily used as an insulator and as a fire retardant and was used extensively in building materials.
• Asbestos fibers can cut and scar the lungs, causing the disease asbestosis.

Noise Pollution

• A sound of any kind is called noise; however, some noises are unnecessary and can cause noise pollution.
• Health problems caused by noise pollution include loss of hearing, high blood pressure, and stress.
• Noise can also cause loss of sleep, which may lead to decreased productivity at work and in the classroom.
• A decibel is the most common unit used to measure loudness, and is abbreviated dB.
• The quietest sound that a human ear can hear is represented by 0 dB.

Light Pollution

• Light pollution does not present a direct hazard to human health, but it does negatively affect the environment.
• The use of inefficient lighting in urban areas diminishes the view of the night sky.
• A more important environmental concern of inefficient lighting is energy waste.
• Energy is wasted when light is directed upward into the night sky and lost to space.
• Examples: lighting on billboards, poor-quality street lights, and the lighting of building exteriors.
• Solutions to this problem: shielding light so it is directed downward, using time controls so that light is used only when needed, and using low-pressure sodium sources, which are the most energy-efficient sources of light.

Acid Precipitation

• Acid precipitation is precipitation, such as rain, sleet, or snow, that contains a high concentration of acids, often because of the pollution of the atmosphere.
• When fossil fuels are burned, they release oxides of sulfur and nitrogen.
• When these oxides combine with water in the atmosphere, they form sulfuric acid and nitric acid, which falls as acid precipitation.
• Acid precipitation can kill living things and can result in the decline or loss of some local animal and plant populations.
• A pH number is a value that expresses the acidity or alkalinity (basicity) of a system.
• Each whole number on the scale indicates a tenfold change in acidity.
• A pH of 7 is neutral, a pH of less than 7 is acidic, and a pH of greater than 7 is basic.
• Pure water has a pH of 7.0, while normal precipitation has a pH of about 5.6.
• Normal precipitation is slightly acidic because atmospheric carbon dioxide dissolves into the precipitation and forms carbonic acid.
• Precipitation is considered acid precipitation if it has a pH of less than 5.0.
• The pH of precipitation varies among different geographic areas.
• The pH of precipitation in the eastern U.S. and Canada ranges from 4.2 to 4.8.
• Most acidic precipitation occurs around Lake Erie and Lake Ontario.

How Acid Precipitation Affects Soils and Plants

• Acid precipitation can cause a drop in the pH of soil and water, called acidification.
• Acidity of soil increases, some nutrients are dissolved and washed away by rainwater.
• Aluminum and other toxic metals are released and possibly absorbed by the roots of plants, causing root damage.
• Sulfur dioxide in water vapor clogs the openings on the surfaces of plants.

Acid Precipitation and Aquatic Ecosystems

• Aquatic animals are adapted to live in an environment with a particular pH range.
• Acid precipitation causes aluminum to leach out of the soil surrounding a lake.
• Aluminum accumulates in the gills of fish and interferes with oxygen and salt exchange.
• Acid shock is the sudden runoff of large amounts of highly acidic water into lakes and streams when snow melts in the spring or when heavy rains follow a drought.
• This phenomenon causes large numbers of fish to die and affects the reproduction of fish and amphibians.
• Offspring that do survive end up with birth defects and cannot reproduce.
• To counteract acid precipitation on aquatic ecosystems, some states in the U.S. and some countries spray powdered limestone (calcium carbonate) to help restore their natural pH.
• Because lime has a pH that is basic, the lime raises the pH of the water.

Acid Precipitation and Humans

• Toxic metals include aluminum and mercury.
• Toxic metals can be released into the environment when soil acidity increases.
• These toxic metals can find their way into crops, water, and fish and then poison the human body.
• Causes on humans can decrease the numbers of fish affects commercial fishermen and the sport-fishing industry.
• Trees are damaged by acid precipitation.
• Acid precipitation can dissolve the calcium carbonate in common building materials, such as concrete.

International Conflict

• One problem in controlling acid precipitation is that pollutants may be released in one geographical area and fall to the ground hundreds of kilometers away.
• Canada and the United States signed the Canada-U.S. Air Quality Agreement in 1991.
• Both countries agreed to reduce acidic emissions that flowed across the Canada-U.S. boundary.