This section addresses, in whole or in part, the following Georgia GPS standard(s):
This section addresses, in whole or in part, the following Benchmarks for Scientific Literacy:
This section addresses, in whole or in part, the following National Science Education Standards:
Types of air pollution
Air pollution can affect our health in many ways with both short-term and long-term effects. Different groups of individuals are affected by air pollution in different ways. Some individuals are much more sensitive to pollutants than are others. Young children and elderly people often suffer more from the effects of air pollution. People with health problems such as asthma, heart and lung disease may also suffer more when the air is polluted. The extent to which an individual is harmed by air pollution usually depends on the total exposure to the damaging chemicals, i.e., the duration of exposure and the concentration of the chemicals must be taken into account.
Examples of short-term effects include irritation to the eyes, nose and throat, and upper respiratory infections such as bronchitis and pneumonia. Other symptoms can include headaches, nausea, and allergic reactions. Short-term air pollution can aggravate the medical conditions of individuals with asthma and emphysema. In the great "Smog Disaster" in London in 1952, four thousand people died in a few days due to the high concentrations of pollution.
Long-term health effects can include chronic respiratory disease, lung cancer, heart disease, and even damage to the brain, nerves, liver, or kidneys. Continual exposure to air pollution affects the lungs of growing children and may aggravate or complicate medical conditions in the elderly. It is estimated that half a million people die prematurely every year in the United States as a result of smoking cigarettes.
One type of air pollution is the release of particles into the air from burning fuel for energy. Diesel exhaust is a good example of this particulate matter . This type of pollution is sometimes referred to as "black carbon" pollution. The exhaust from burning fuels in automobiles, homes, and industries is a major source of pollution in the air.
Smog is a type of outdoor pollution caused by chemical reactions between pollutants derived from various sources, such as automobile exhaust and industrial emissions. Cities are often centers of these types of activities, and many suffer from the effects of smog, especially during the warm months of the year.
Air pollution is dispersed differently, depending on the geographical location, temperature, wind and weather factors. However, sometimes pollution does not disperse, and can build up to dangerous levels. A temperature inversion occurs when air close to the Earth is cooler than the air above it. Under these conditions the pollution cannot rise and be dispersed. Cities surrounded by mountains also experience trapping of pollution. Inversion can happen in any season. Winter inversions are likely to cause particulate and cabon monoxide pollution. Summer inversions are more likely to create smog.
Another consequence of outdoor air pollution is acid rain.
The falling of acids and acid-forming compounds from the atmosphere to Earth’s surface is referred to as acid deposition. Acid deposition is commonly know as acid rain when it occurs as the wet deposition of droplets of acids and acid-forming compounds.
Natural precipitation is slightly acidic with a pH of 5.0 to 5.6.
Because of acid deposition, typical rain in the eastern United States is now about ten times more acidic with a pH of 4.3.
In some areas, rain is 100 times more acidic, with a pH of 3.
Acid deposition can be a serious regional problem, particularly in areas downwind from coal-burning power plants, smelters, factories, and large urban areas.
Acid deposition can have many harmful ecological effects in both aquatic and terrestrial systems. It can damage tree foliage directly and make trees more susceptible to other stresses such as cold temperatures, diseases, insects, droughts, etc.
In lakes, acid deposition can kill fish and can promote the conversion of moderately toxic inorganic mercury compounds into highly toxic methylmercury.
It also contributes to human respiratory diseases such as bronchitis and asthma.
Certain gases in the atmosphere trap heat in the lower atmosphere (troposphere). This phenomenon has been referred to as the greenhouse effect.
Without the natural thermal insulation of the natural greenhouse effect, the earth would be covered by ice, and life as we know it would not exist.
The amount of heat trapped in the troposphere depends mainly on the concentrations of heat-trapping greenhouse gases and the length of time they stay in the atmosphere.
The major greenhouse gases are:
The two predominant greenhouse gases are water vapor (controlled by the hydrologic cycle), and carbon dioxide (controlled by the global carbon cycle).Water vapor
Water vapor added to the atmosphere by human activities has little effect on the greenhouse effect.
What might cause carbon dioxide levels to rise?
Atmospheric levels of carbon dioxide, CFCs, methane, and nitrous oxides have risen significantly in recent decades.
The total amount of CO2 in the atmosphere has increased by about 25% since the beginning of the industrial revolution. The accumulation of CO2 over the last century has added as much heat to the Earth's climate system as would a one half percent increase in the sun's energy output.
Since the late 1800's, the mean global temperature has risen by about 0.3o - 0.6oC, and over the last 45 years, the temperature has increased by about 0.2 - 0.3oC. Recent years have been among the warmest on record.
The increase in these greenhouse gases is projected to increase the earth’s natural greenhouse effect and lead to global warming.
Possible consequences of global warming include:
Many uncertainties remain with respect to the exact consequences of global warming.
The ozone layer exists in the stratospheric layer of the earth’s atmosphere where ozone concentrations are nearly one thousand times higher than in the troposphere.
Ozone is produced by lightning and solar irradiation of oxygen molecules.
Ozone is formed by reactions that start with the splitting of O2to form two atomic oxygen (O) atoms. Atomic oxygen (O) will react with another O2 molecule to form ozone (O3).
Ozone can be destroyed by catalytic reactions involving chlorine, bromine, etc.
Chlorine has been directly implicated in the formation of the Antarctic ozone hole.
Ozone protects life on earth by absorbing most incoming solar ultraviolet radiation.
Ozone depletion is another result of pollution. Chemicals released by our activities affect the stratosphere , one of the atmospheric layers surrounding earth. The ozone layer in the stratosphere protects the earth from harmful ultraviolet radiation from the sun. Release of chlorofluorocarbons (CFC's) from aerosol cans, cooling systems and refrigerator equipment removes some of the ozone, causing "holes"; to open up in this layer and allowing the radiation to reach the earth. Ultraviolet radiation is known to cause skin cancer and has damaging effects on plants and wildlife.
Return to Earth & Space Science page
Return to Georgia Geoscience Online
Page created by Pamela J.W. Gore
Georgia Perimeter College,
Page created March 26, 2005
Updated May 16, 2008