Background on Pollution


Major Air Pollutants

Pollutant Sources Effects
A colorless gas that is the major constituent of photochemical smog at the Earth’s surface. In the upper atmosphere (stratosphere), however, ozone is beneficial, protecting us from the sun’s harmful rays.
Ozone is formed in the lower atmosphere as a result of chemical reactions between oxygen, volatile organic compounds, and nitrogen oxides in the presence of sunlight, especially during hot weather. Sources of such pollutants include vehicles, factories, landfills, industrial solvents, and numerous small sources such as gas stations, and farm and lawn equipment. Ozone causes significant health and environmental problems at the Earth’s surface. It can irritate the respiratory tract, produce impaired lung function and cuase throat irritation, chest pain, cough, and lung inflammation. It can also reduce the yield of agricultural crops and injure forests and other vegetation. Ozone is the major most injurious pollutant to plan life.
Carbon Monoxide
Odorless and colorless gas emitted in the exhaust of motor vehicles and other kinds of engines, where there is incomplete fossil fuel combustion.
Automobiles, buses, trucks, small engines, and some industrial processes. High concentrations can be found in confined spaces like parking garages, poorly ventilated tunnels, or along roadsides during periods of heavy traffic. Reduces the ability of blood to deliver oxygen to vital tissues, affecting primarily the cardiovascular and nervous systems. Lower concentrations have been shown to adversely affect individuals with heart disease; higher concentrations can cause dizziness, headaches, and fatigue.
Nitrogen Dioxide
Light brown gas at lower concentrations; in higher concentrations becomes an important component of unpleasant-looking brown, urban haze.
Result of burning fuels in utilities, industrial boilers, cars, and trucks. One of the major pollutants that cause smog and acid rain. It can harm humans and vegetation when concentrations are high.
Particulate Matter
Solid matter or liquid droplets from smoke, dust, fly ash, and condensing vapors that can be suspended in the air for long periods of time.
Industrial processes, smelters, automobiles, burning industrial fuels, wood smoke, dust from paved and unpaved roads, construction, and agricultural ground breaking. These microscopic particles can affect breathing and respiratory health, causing increased respiratory disease and lung damage, and possibly premature death.
Sulfur Dioxide
Colorless gas; odorless at low concentrations but pungent at very high concentrations
Emitted largely from industrial, institutional, utility and apartment-house furnaces and boilers, as well as petroleum refineries, smelters, paper mills, and chemical plants. One of the major pollutants that cause smog. Can also, at high concentrations, affect human health, especially among asthmatics, and acidify lakes and streams.
Lead and lead compounds can adversely affect human health through either ingestion of lead-contaminated soil, dust, pain, or direct inhalation.
Transportation sources using lead in their fuels, coal combustion, smelters, car battery plants, and combustion of garbage containing lead products. Elevated lead levels can adversely affect mental development, kidney function, and blood chemistry. Young children are particularly at risk.
Toxic Air Pollutants
Includes pollutants such as arsenic, asbestos, and benzenes.
Chemical plants, industrial processes, motor vehicle emissions and fuels, and building materials. Known or suspected to cause cancer, respiratory effects, birth defects, and reproductive and other serious health effects.
Stratospheric Ozone Depleters
Chemicals such as chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform. These chemicals rise to the upper atmosphere where they destroy the protective ozone layer.
Industrial household refrigeration, cooling and cleaning processes, car and home air conditioners, some fire extinguishers, and plastic foam products. Increased exposure to UV radiation could potentially cause an increase in skin cancer, cataracts, suppression of the human immune response system, and environmental damage.

The Greenhouse Effect

Gases that build up in the atmosphere that may include global climate change. They include carbon dioxide, methane, and nitrous oxide.
The main man-made source of carbon dioxide emissions is fossil fuel combustion for energy-use and transportation. Methane comes from landfills, cud-chewing livestock, coal mines, and rice paddies. Nitrous oxide results from industrial processes, such as nylon fabrication. The extent of the effects of climate change on human health and the environment is uncertain, but could include increased global temperature, increased severity and frequency of storms, and other “weather extremes,” melting of the polar ice cap, and sea-level rise.

Major Water Pollutants

Pollutant Sources Effects
Petroleum Products
Oil and chemicals derived from oil are used for fuel, lubrication, plastics manufacturing, and many other purposes.
These petroleum products get into water mainly by means of accidental spills from ships, tanker trucks, pipelines, and leaky underground storage tanks. Many petroleum products are poisonous if ingested by animals, and spilled oil damages the feathers of birds and the fur of animals, often causing death. IN addition, spilled oil may be contaminated with other harmful substances, such as PCBs (polychlorinated biphenyls).
Pesticides and Herbicides
Chemicals used to kill unwanted animals and plants, for instance on farms or in suburban yards.
These chemicals may be collected by rainwater runoff and carried into streams, especially if these substances are used in excess. Some of these chemicals are biodegradable and quickly decay into harmless or less harmful forms, while others are non-biodegradable and remain dangerous for a long time. When animals consume plants that have been treated with certain non-biodegradable chemicals, such as chlordane and DDT, these chemicals are absorbed into the tissues or organs of the animals. When other animals feed on these contaminated animals, the chemicals are passed up the food chain. The concentration of the pollutant increases through biomagnification, so that animals at the top of the food chains, may suffer cancers, reproductive problems, and death. Many drinking water supplies are contaminated with pesticides from widespread agricultural use.

Heavy Metals
such as copper, lead, mercury, and selenium.

These metals get into water from many sources, including industries, automobile exhaust, mines, and even natural soil.  Lead can get into water from lead pipes and solder in older water systems. Like pesticides, heavy metals become more concentrated as animals feed on plants and are consumed by other animals. When they reach high levels in the body, heavy metals can be immediately poisonous, or can result in long-term problems similar to those caused by pesticides and herbicides. For example, cadmium in fertilizer derived from sewage sludge can be absorbed by crops. If these crops are eaten by humans in sufficient amounts, the metal can cause diarrhea and, over time, liver and kidney damage. Children exposed to lead in water can suffer mental retardation.

Hazardous Waste
Chemical wastes that are either toxic (poisonous), reactive (capable of producing explosive or toxic gases), corrosive (capable of corroding steel), or ignitable (flammable).

These chemical wastes can pollute water supplies if they are stored or treated improperly. PCBs, a class of chemicals once widely used in electrical equipment such as transformers, can get into the environment through oil spills and can reach toxic levels as organisms eat one another. River and lake pollution can be toxic enough to kill animal and plant life immediately, or it can injure slowly. For example, fluoride concentrates in teeth and bone, and too much fluoride in water may cause dental and bone problems. Like pesticides and heavy metals, hazardous wastes become more concentrated as animals feed on plants and are consumed in turn by other animals. When they reach high levels in the body, hazardous wastes can be immediately poisonous, or can result in long-term problems similar to those caused by pesticides and herbicides and heavy metals.

Excess organic matter
Plants and algae that grow in excess due to fertilizer and other nutrients from farm and garden runoff.

Fertilizers and other nutrients used to promote plant growth on farms and in gardens may find their way into water. At first, these nutrients encourage the growth of plants and algae in water. However, when the plant matter and algae die and settle underwater, microorganisms decompose them. The process of decomposition, these microorganisms consume oxygen that is dissolved in the water. Oxygen levels in the water may drop to such dangerously low levels that oxygen-dependent animals in the water, such as fish, die. This process of depleting oxygen to deadly levels is called eutrophication. The Mississippi River carries an estimated 1.5 million metric tons of nitrogen pollution into the Gulf of Mexico each year. The resulting dead zone in the Gulf each summer is about the size of Massachusetts.

Soil particles carried to a streambed, lake, or ocean that can be a pollutant if it is present in large enough amounts.

Soil erosion which can be produced by the removal of trees near waterways, or that is carried by rainwater and floodwater from croplands, strip mines, and roads. Sedimentation can damage a stream or lake by introducing too much nutrient matters that leads to eutrophication. Sedimentation can also cover streambed gravel in which many fish, such as salmon and trout, lay their eggs.

Infectious Organisms
Waterborne diseases occur when parasites or other disease-causing microorganisms are transmitted through contaminated water, especially when conducted by animal and human feces. These diseases include typhoid, intestinal parasites, and most of the diarrheal diseases caused by bacteria, parasites, and viruses.

Human migration has disseminated infectious disease and brought people into contact with new pathogens; environmental change has expanded the conditions for native micro-organisms to emerge as significant human pathogens; modern techniques in animal conservation, as well as some of the more traditional methods of livestock farming, create a risk from new zoonotic diseases (an infectious disease which normally circulates in an animal host but that can be contracted by humans); sewage pollution is also a major contributor.

A study by CDC estimated that about 900,000 people get sick annually in the United States because of organisms in their drinking water, causing around 900 deaths. Many disease-causing organisms that are present in small numbers in most natural waters are considered pollutants when found in drinking water. Parasites can cause illness, especially in people who are very old or very young, and in people who are already suffering from other diseases and occasionally are found in urban water supplies.

Thermal Pollution
An upward or downward temperature change in a natural body of water caused by human influence.

Water is often drawn from rivers, lakes, or the ocean for use as a coolant in factories and power plants. The water is usually returned to the source warmer than when it was taken. Thermal pollution can also be caused by the removal of trees and vegetation that shade and cool streams. Even small temperature changes in a body of water can drive away the fish and other species that were originally present, and attract other species in place of them. Thermal pollution can accelerate biological processes in plants and animals or deplete oxygen levels in water. The result may be fish and other wildlife deaths near the discharge source.

Major Land Pollutants

Pollutant Sources Effects
Agriculture Accumulation of animal manures, excessive input of chemical fertilizers, illegal dumping of tainted crops on land.

The effects of land pollution include: exterminates wild life

acid rain kills trees and other plants; vegetation that provides food and shelter is destroyed; it can seriously disrupt the balance of nature, and, in extreme cases, can cause human fatalities; pesticides can damage crops; kill vegetation; and poison birds, animals, and fish; most pesticides kill or damage life forms other than those intended, for example, pesticides used in an effort to control or destroy undesirable vegetation and insects often destroy birds and small animals; some life forms develop immunity to pesticides used to destroy them; pollutants can contaminate groundwater
Mining and Quarrying

Use of explosives to blow up mines. Use of machineries which emit toxic byproducts and leaks to the ground.

Sewage Sludge Improper sanitation system causes sludge to leak at surrounding soil. Same
Dredged Spoils Improper method of dredging at fertile land causes soil infertility, leaving the soil more prone to external pollution. Same

Improper waste disposal system causes waste accumulation. Improper sanitation system.

Demolition and Construction Non-biodegradable rubbles or debris which are not cleared settle in the soil and undergo chemical reactions, increasing soil toxicity. Same
Industrial Poisonous/toxic emissions of gases which are not filtered or neutralized. Same


WHO - World Health Organization
Grinning Planet