Section 1: What Causes Air Pollution

Chapter 12: Air

• Clean air consists mostly of nitrogen and oxygen gas as well as very small amounts of argon, carbon dioxide, and water vapor.

• When harmful substances build up in the air to unhealthy levels, the result is air pollution.

• Most air pollution is the result of human activity.

• Some does come from natural sources such as volcanic eruptions.

Primary and Secondary Pollutants

• A pollutant that is put directly into the air by human activity is called a primary pollutant. Soot from smoke is an example.

• Secondary pollutants form when primary pollutants react with other primary pollutants or with naturally occurring substances such as water vapor. Ground level ozone is an example. This happens when UV rays cause emissions from vehicles to react with oxygen in the atmosphere.

Sources of Primary Air Pollution

• Household products, power plants, and motor vehicles are sources of primary air pollutants such as carbon monoxide, nitrogen oxide, sulfur dioxide, and chemicals called volatile organic compounds (VOCs).

• Carbon monoxide is an important component in the exhaust from vehicles.

• Nitrogen oxides come from vehicles and coal burning power plants.

• Sulfur dioxide forms when coal and oil are burned. Power plants, refineries, and metal smelting are contributors as well.

• Most VOCs are from vehicles and gas station spillage.

The History of Air Pollution

• The problem is not new :

• 2,000 years ago, Seneca, a Roman philosopher, complained about the foul air in Rome.

• In 1273, King Edward I ordered the burning of sea coal illegal.

• Air quality is worse today because of industrial societies burn large amounts of fossil fuels.

• Most air pollution comes from motor vehicles and industry.

Motor Vehicle Emissions

• Almost 1/3 of our air pollution from gasoline burned by vehicles.

• In 1998 Americans drove over 2.6 trillion miles and 90% of that was passenger vehicles.

Controlling Vehicle Emissions

• The Clean Air Act, passed in 1970, gives the EPA the authority to regulate vehicle emissions in the U.S.

• The EPA called for the gradual elimination of lead in gasoline. As a result, lead pollution has been reduced by more than 90%.

• Catalytic converters, which are now required, clean exhaust gases of pollutants before the pollutants are able to escape the tailpipe.

• Cars today burn fuel 35% more efficiently and with 95% fewer emissions.

California Zero Emission Vehicle Program

• In California, vehicle emissions account for more than half of the ozone and particulate matter that pollutes the air.

• In 1990, the state's Air Resource Board established the Zero Emission Vehicle (ZEV) program.

• Battery powered vehicles are the only true ZEVs at the moment.

• There are two types of partial ZEVs. Hybrids which are powered by both battery and gasoline and methanol fuel cell cars (which are still developmental prototypes).

Industrial Air Pollution

• Many industries and power plants burn fossil fuels to produce energy.

• Burning fossil fuels releases sulfur dioxide and nitrogen oxides into the air.

• Power plants emit at least 2/3 of all sulfur dioxide and more than 1/3 of all nitrogen oxides that pollute the air.

• Dry cleaning also produces VOCs as do oil refineries, chemical manufacturing plants, furniture refinished, and automobile repair shops.

Regulating Air Pollution from Industry

• The Clean Air Act requires many industries to use scrubbers to remove some of the more harmful substances that would otherwise pollute the air.

• A scrubber is a machine that moves gases through a water spray to dissolve many pollutants.

• Electrostatic precipitators are used in cement factories and coal burning power plants. Gas containing dust particles are blown through an electrically charged chamber causing the particles to stick together and the sides of the chamber. Clean gas is released and particle can be collected and removed.

• Electrostatic precipitators remove 22 million metric tons of ash every year.

Smog

• When air pollution hangs over urban areas and reduces visibility, it is called smog.

• 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 air near the surface. Warm air rises through the cooler air above it carrying pollutants away from the ground.

• Sometimes pollution is trapped near the Earth's surface. Usually air temperature decreases with altitude, but sometimes a temperature inversion occurs. When this happens, the warmer air keeps the cooler air at the surface from moving upward trapping pollutants in the cooler air closer to the surface.

• Cities in valleys have a greater chance of this occurring.

Section 2: Air, Noise, and Light Pollution

• The very young and very old with heart or lung problems are most susceptible.

• Death certificates will list diseases like emphysema and lung cancer instead of air pollution.

• Americans pay tens of billions of dollars annually to treat respiratory diseases caused by air pollution.

Short Term Effects of Air Pollution on Health

• Many effects of air pollution are short-term and reversible IF exposure decreases.

• Short-term effects include headache, nausea, irritation to the eyes, nose, and throat, tightness in the chest, coughing, and upper respiratory infections like bronchitis and pneumonia.

• People who have asthma and emphysema can have symptoms worsen.

Long Term Health Effects of Air Pollution

• Long term effects include emphysema, lung cancer, and heart disease.

• Long term exposure may worsen symptoms especially in older people

Sick Building Syndrome

• Chemicals used to make carpets, building materials, paints, and furniture are the major sources of indoor pollutants.

• Buildings that have very poor air quality have a condition called sick-building syndrome.

• This is most common in hot places where buildings are tightly sealed to keep the heat out.

• Identifying and removing the sources of indoor pollutants is the most effective way to maintain good indoor air quality.

• Ventilation is necessary for good indoor air quality.

Radon Gas

• Radon is a colorless, odorless, tasteless gas that is radioactive. It is produced by the decay of uranium.

• Radon can seep through the cracks and holes in the foundation of homes, offices, schools, etc. where it sticks to dust particles.

• In the lungs, radon can destroy the genetic material in the cells that line air passages.

• Radon is the second leading cause of lung cancer in the U.S.

Asbestos

• Several minerals that form in long, thin fibers and that are valued for their strength and resistance to heat are called asbestos.

• Asbestos is primarily used as an insulator and fire retardant that was used extensively in building materials.

• The U.S. banned the use of asbestos in the early 1970's.

• Asbestos fibers that are inhaled can cut and scar the lungs causing asbestosis. People who have this have difficulty breathing and can die of heart failure.

Noise Pollution

• Unwanted sound is noise pollution.

• It is irritating, and it damages our hearing. Hearing loss has doubled in the U.S. in the past 30 years. About 12% of teens have permanent hearing loss likely due to the use of portable listening devices. The National Institutes of Health say the safe threshold for MP3 players is 85 dB for 8 hours.

• Sound intensity is measured in decibels (dB).

• Noise pollution can be controlled by devices such as mufflers on lawn mowers and vehicles.

Light Pollution

• Light pollution does not present a direct hazard to human health.

• Light pollution in urban areas diminishes our view of the night sky.

• The more important concern of light pollution is wasted energy.

• Solutions include shields to direct light downward, using timers, and low-pressure sodium sources which are more efficient.

Section 3: Acid Precipitation

What Causes Acid Rain

Acid precipitation is precipitation such as rain, sleet, or snow that contains a high concentration of acids.

When fossil fuels a burned, they release oxides of sulfur and nitrogen. When these oxides combine with water vapor, they form sulfuric and nitric acid which fall as acid precipitation.

It can kill living things and cause decline or loss of plant and animal populations.
A pH number is a measure of how acidic or basic a substance is. The lower the pH, the more acidic the substance is. The higher the pH the more basic a substance is. Pure water has a pH of 7.
Natural rain is slightly acidic because carbon dioxide dissolves into the precipitation forming carbonic acid. Normal rain has a pH of about 5.6. Acid rain has a pH of less than 5.

How Acid Precipitation Affects Soil and Plants

Acid precipitation can cause a drop in the pH of soil and water. This increase is called acidification.

This changes the balance of a soil's chemistry. This causes some nutrients to dissolve and wash away. It also causes aluminum and other toxic metals to be released and absorbed by plant roots.

Acid Precipitation and Aquatic Ecosystems

Aquatic animals are adapted to live in an environment with a particular pH range. If the pH of the water changes, the fish and other organisms can die.

Acid precipitation causes aluminum to leech out of the soil, and aluminum in the gills of fish interferes with oxygen and salt exchange.

Effects are worst in the spring when snow melts and rushes into lakes and rivers.

The sudden influx of acidic water is called acid shock.

Acid Precipitation and Humans

Toxic metals like aluminum and mercury can be released into the environment when soil acidity increases. These metals find their way into crops, water, and fish; then they poison humans.

There is a correlation between acid rain and respiratory problems.

A decrease in the number of fish affects commercial fishermen. Forestry is affected when the trees are damaged.

Calcium carbonate can dissolve which affects many monuments and creates sink holes.

International Conflict and Cooperation

One problem is that pollutants released in one area may fall to the ground hundreds of miles away.

Acid precipitation is an international problem. Canada and the U.S. signed the Canada-U.S. Air Quality Agreement in 1991. Both countries agreed to reduce emissions that flow across the U.S. Canada border.

Sulfur dioxide emissions have reduced significantly because agreements like this.

China still burns large amounts of high-sulfur without pollution controls.

Chapter 13: Atmosphere and Climate Change

Section 1: Climate and Climate Change

· Weather is the state of the atmosphere at any given moment.

· Climate is the long-term prevailing weather conditions at a particular place based upon records.

What Factors Determine Climate

· Climate is determined by a variety of factors including latitude, atmospheric circulation patterns, oceanic circulation patterns, local geography, solar activity, and volcanic activity.

· Latitude, however, is the most important factor.

Latitude

· Latitude is the distance from the equator measured in degrees north or south

· The equator is 0 degrees latitude; the North Pole is 90 degrees north, and the South Pole is 90 degrees south.

Low Latitudes

· Latitude influences climate because the amount of solar energy an area of Earth receives depends on its latitude.

· More solar energy falls near the equator than the poles.

· Near the equator, night and day are about 12 hours each. Temperatures are constant year round. There are no summer and winter.

High Latitudes

· In regions close to the pole, the amount of energy arriving at the surface is reduced.

· Sunlight strikes at oblique angles and spreads over a larger surface area than at the equator.

· Average temperatures are lower because of this, and the amounts of daylight vary.

· Some places get 16 hours of daylight in the summer and 8 in the winter. Near the poles, the sun sets for only a few hours each day in the summer and rises for only a few hours in the winter.

Atmospheric Circulation

· Three important properties of air illustrate how air circulation affects climate.

· First, cold air sinks because it is more dense than hot air.

· Second, warm air rises expanding and cooling as it rises.

· Third, warm air can hold more water vapor than cold air can. When warm air cools, the water vapor may condense into liquid water forming rain, snow, or fog.

· Solar energy heats the ground which warms the air above it. The warm air rises and cool air replaces it. This movement of air within the atmosphere is wind.

· Because Earth rotates and different latitudes receive different amounts of solar energy, the pattern of global atmospheric circulation results.

· This pattern determine Earth's precipitation pattern.

· Air near Earth's surface at the equator becomes very warm and able to hold a lot of water vapor. As it rises and cools it loses some of its ability to hold the water, so areas near the equator get more rain.

Global Circulation Patterns

· Cool air normally sinks, but cool air at the equator cannot sink because hot air is rising below the cool air.

· The cool air rises and is forced away from the equator toward the poles.

· At about 30 degrees north and south, some of this cool air sinks back down to the Earth's surface.

· As it descends, it becomes warmer. This now warm, dry air moves across the surface causing water to evaporate from the land below creating dry conditions.

· Air descending at 30 degrees north or south either move toward the equator or the poles.

· At about 60 degrees north or south, this air collide with cold air traveling from the poles.

· Warm air rises reaching the top of the troposphere, but a small amount returns back to the circulation pattern between 60 and 30 degrees.

· Most is uplifted toward the poles creating very cold deserts.

Prevailing Winds