Pollution

Environmental pollution is the release of environmental contaminants, generally resulting from human activity. Carbon monoxide, sulfur dioxide and nitrogen oxides produced by industry and motor vehicles are common air pollutants. Sunlight converts nitrogen oxides and hydrocarbons to ozone or smog. Water pollutants may consist of a wide range of organic and inorganic chemicals such as heavy metals, petrochemicals, chloroform, and bacteria. Water pollution may also occur in the form of thermal pollution and oxygen depletion. Soil contamination is an important aspect of environmental pollution; this phenomenon occurs when chemicals are released by spill or underground storage tank leakage. Among the most significant soil contaminants are hydrocarbons, heavy metals, MTBE, herbicides, pesticides and chlorinated hydrocarbons. The U.S., Russia, China and Japan are the world leaders in air pollution emissions; however, Canada is the number two country on a per capita basis.

Categories

Traditional forms of pollution have included:

• air pollution, involving the release of chemicals and particulates into the atmosphere
• water pollution, which is also often associated with soil contamination due to the involvement of groundwater and runoff

A modern addition is radioactive contamination, after scientific breakthroughs involving atomic physics in the 20th century.

Broader contemporary considerations of pollution also embrace:

• thermal pollution, an aspect of water pollution
• noise pollution, which now encompasses marine environments as well as urban and industrial settings
• light pollution, owing in part to awareness afforded by the field of astronomy, gaining formal recognition in the 1980s

Sources and causes

Arguably the principal source of air pollutants worldwide is motor vehicle emissions. While the U.S. has adopted stringent emissions controls, the EU has not been as assertive in this field; nevertheless, the U.S. is still the leading contributor to mobile source air emissions merely due to the very high number of vehicle miles travelled per capita. Underdeveloped countries lag severely in emission controls on motor vehicles, especially roadway vehicles, and on a per vehicle mile travelled basis produce many times the emissions of the U.S fleet.

Principal stationary pollution sources include chemical plants, oil refineries, nuclear waste disposal activity, incinerators, large animal farms, PVC factories, metals production factories, plastics factories, and other heavy industry.

Some of the more common soil contaminants are chlorinated hydrocarbons (CFH), heavy metals such as lead, which is found in lead paint and until recently in gasoline, MTBE, cadmium, which is found in rechargeable batteries, chromium, zinc, arsenic and benzene. Ordinary municipal landfills are the source of many chemical substances entering the soil environment (and often groundwater), emanating from the wide variety of refuse accepted, especially substances illegally discarded there, or from pre-1970 landfill that may have been subject to little control in the U.S. or EU.

Pollution can be the consequence of a natural disaster. For example hurricanes often involve water contamination from sewage, and petrochemical spills from ruptured boats or automobiles. Larger scale and environmental damage is not uncommon when coastal oil rigs or refineries are involved. Some sources of pollution, such as nuclear power plants or oil tankers, can produce widespread and potentially hazardous releases when accidents occur.

In the case of noise pollution the dominant source class is the motor vehicle, producing about ninety percent of all unwanted noise worldwide.

Effects on human health

Pollutants are known to be causative for many diseases, including cancer, lupus, immune diseases, allergies, and asthma. Higher levels of background radiation have lead to an increased incidence of cancer and mortality associated with it worldwide. Some illnesses are named after the sites of human tragedy where specific pollutants were first formally implicated as the culprit. One example is Minamata disease, which is caused by mercury compounds.

Noise pollution induces high blood pressure, stress and sleep disturbance. Persistent adverse air quality above certain threshholds impact mortality rates. Ozone pollution can cause sore throats, inflammation, chest pain and congestion. Skin irritations and rashes may arise when oil is spread in the local environment.

Regulation and monitoring

United States

The United States Environmental Protection Agency (EPA) has established threshhold standards for air pollutants to protect human health on January 1,1970. One of the ratings chemicals are given is carcinogenicity. In addition to the classification "unknown", designated levels range from non-carcinogen, to likely, and known carcinogen. But some scientists have said that the concentrations which most of these levels indicate are far too high and the exposure of people should be less. In 1999, the United States EPA replaced the Pollution Standards Index (PSI) with the Air Quality Index (AQI) to incorporate new PM2.5 and Ozone standards.

The U.S. has a maximum fine of US$25,000 for dumping toxic waste. However, many large manufacturers decline to dispute violations, as they can easily afford this small fine. The state of California Cal/EPA Office of Environmental Health Hazard Assessment (OEHHA) has maintined an independent list of substances with product labeling requirements as part of proposition 65 since 1986.

Europe

Generally the European states lag significantly behind the United States in meaningful environmental regulation, including air quality standards, water quality standards, soil contamination cleanup, indoor air quality and noise regulations. For example, the EU is presently entertaining use of the carcinogen MTBE as a widespread gasoline additive, a chemical which has been in the process of phaseout in the U.S. for over a decade. In the year 200 UK Air Quality Regulations were established and further amended in 2002; since, there has been British harmonization with EU regulations.

International

The Kyoto Protocol is an amendment to the United Nations Framework Convention on Climate Change (UNFCCC), an international treaty on global warming. It also reaffirms sections of the UNFCCC. Countries which ratify this protocol commit to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases. A total of 141 countries have ratified the agreement. Notable exceptions include the United States and Australia.

History

Prehistory

Humankind has had some effect upon the natural environment since the paleolithic era during which the ability to generate fire was acquired. In the iron age, the use of tooling led to the practice of metal grinding on a small scale and resulted in minor accumulations of discarded material probably easily dispersed without too much impact. Human wastes would have polluted rivers or water sources to some degree. However, these effects could be expected predominantly to be dwarfed by the natural world.

Ancient Cultures

The first advanced civilizations of China, Egypt, Persia, Greece and Rome increased use of water for primitive industrial processes, increasingly forged metal and created fires of wood and peat for more elaborate purposes (for example, bathing, heating). Still, at this time the scale of activiity did not disrupt ecosystems or greatly alter air or water quality.

Middle Ages

The dark ages and early Middle Ages were a great boon for the environment, in that industrial activity fell, and population levels did not grow rapidly. Toward the end of the Middle Ages populations grew and concentrated more within cities, creating pockets of readily evident contamination. At certain times and places air pollution levels were recognizable as health issues, and water pollution in population centers was a serious medium for disease transmission from the untreated human waste.

Since travel and widespread information were less common, there did not exist a more general context than that of local consequences in which to consider pollution. Foul air would have been considered a nuissance and wood, or eventually, coal burning produced smoke, which in sufficient concentrations could be a health hazard in proximity to living quarters. Septic contamination or poisoning of a clean drinking water source was very easily fatal to those who depended on it, especially if such a resource was rare. Superstitions predominated and the extent of such concerns would probably have been little more than a sense of moderation and an avoidance of obvious extremes.

First Recognition

But gradually increasing populations and the proliferation of basic industrial processes saw the emergence of a civilization that began to have a much greater collective impact on its surroundings. It was to be expected that the beginnings of environmental awareness would occur in the more developed cultures, particularly in the densest urban centers. The first medium warranting official policy measures in the emerging western world would be the most basic: the air we breathe.

King Edward I of England banned the burning of sea-coal by proclamation in London in 1361, after its smoke had become a problem. But the fuel was so common in England that this earliest of names for it was acquired because it could be carted away from some shores by the wheelbarrow. Air pollution would continue to be a problem there, especially later during the industrial revolution, and extending into the recent past with the Great Smog of 1952. This same city also recorded one of the earlier extreme cases of water quality problems with the Great Stink on the Thames of 1858, which lead to construction of the London sewerage system soon afterward.

It was the industrial revolution that gave birth to environmental pollution as we know it today. The emergence of great factories and consumption of immense quantities of coal and other fossil fuels gave rise to unprecedented air pollution and the large volume of industrial chemical discharges added to the growing load of untreated human waste. Chicago and Cincinnati were the first two American cities to enact laws ensuring cleaner air in 1881. Other cities followed around the country until early in the 20th century, when the short lived Office of Air Pollution was created under the Department of the Interior. Extreme smog events were experienced by the cities of Los Angeles and Donora, Pennsylvania in the late 1940s, serving as another public reminder.

Modern Awareness

Though these were the basis for later federal legislation to come, amazingly not much notice of environmental pollution was taken in the first half of the twentieth century. The predominant perception was positive, with life expectancies growing as a result of greater food availability and better medical care. Despite being a long-running undercurrent, it was not until the 1960s in the United States that widespread awareness of the issue gained popular footing. In the U.S., between the mid-1950s and early 1970s the National Air Pollution Control Act, the Clean Air Act, the Clean Water Act and the National Environmental Policy Act were passed.

Consciousness has been heightened by occasional but particularly catastrophic incidents of local pollution. From PCB dumping in the Hudson River resulting in a ban by the EPA on consumption of its fish in 1974; long-term dioxin contamination at Love Canal starting in 1947, becoming a national news story in 1978 and leading to the Superfund legislation of 1980; and legal proceedings in the 1990s over Chromium-6 releases in California--the champions of whose victims, such as Erin Brockovich, became famous; very prominent examples of soil and water contamination have been witnessed in mainstream culture. Formerly industrial land under consideration for pollution concerns became common enough in public policy circles that it was officially given the name brownfield, a term now common in city planning. DDT has been banned in most of the developed world after its environmental impact was understood.

In the last stages of WWII, the thermonuclear bomb presented a paradigm shift in weaponry. But long after the destruction caused by its initial deployment, it left behind something previously unknown: radioactive contamination. Nuclear weapons continued to be tested in the Cold War, sometimes near inhabited areas, especially in the earlier stages of their development. The toll on the worst-affected populations and the growth since then in understanding about the critical threat to human health posed by radioactivity has also been a prohibitive complication associated with nuclear power. Though extreme care is practiced in that industry, the potential for disaster suggested by incidents such as those at Three Mile Island and Chernobyl pose a lingering specter of public mistrust. One legacy of nuclear testing has been significantly raised levels of background radiation.

International catastrophes such as the wreck of the Amoco Cadiz oil tanker off the coast of Brittany in 1978 and the Bhopal industrial disaster in 1984 have demonstrated the universality of such events and the scale on which efforts to address them needed to engage. The borderless nature of the atmosphere and oceans inevitably resulted in the implication of pollution on a planetary level with the issue of global warming. Growing evidence of local and global pollution and an increasingly informed public over time have given rise to environmentalism and the environmental movement, which generally seek to limit human impact on the environment.

Perspectives

The earliest precursor of pollution generated by life forms would have been a natural function of their existence. The attendant consequences on viability and population levels fell within the sphere of natural selection. These would have included the demise of a population locally or ultimately, species extinction. Processes that were untenable would have resulted in a new balance brought about by changes and adaptations. At the extremes, for any form of life, consideration of pollution is superceded by that of survival.

For mankind, the factor of technology is a distinguishing and critical consideration, both as an enabler and an additional source of byproducts. Short of survival, human concerns include the range from quality of life to health hazards. Since science holds experimental demonstration to be definitive, modern treatment of toxicity or environmental harm involves defining a level at which an effect is observable. Common examples of fields where practical measurement is crucial include automobile and industrial emissions, toxicology (eg LD50), and medicine.

"The solution to pollution is dilution", is a dictum which summarizes a traditional approach to pollution management whereby sufficiently diluted pollution is not harmful. It is well-suited to some other modern, locally-scoped applications such as laboratory safety procedure and hazardous material release emergency management. But it assumes that the dilutant is in virtually unlimited supply for the application or that resulting dilutions are acceptable in all cases.

Such simple treatment for environmental pollution on a wider scale might have had greater merit in earlier centuries when physical survival was often the highest imperative, human population and densities were lower, technologies were simpler and their byproducts more benign. But these are often no longer the case. Furthermore, advances have enabled measurement of concentrations not possible before. The use of statistical methods in evaluating outcomes has given currency to the principle of probable harm in cases where assessment is warranted but resorting to deterministic models is impractical or unfeasible. In addition, consideration of the environment beyond direct impact on human beings has gained prominence.

Yet in the absence of a superceding principle, this older approach predominates practices throughout the world. It is the basis by which to gauge concentrations of effluent for legal release, exceeding which penalties are assessed or restrictions applied. The regressive cases are those where a controlled level of release is too high or, if enforceable, is neglected. Migration from pollution dilution to elimination in many cases is confronted by challenging economical and technological barriers.

Controversy

Industry and concerned citizens have battled for decades over the significance of various forms of pollution. Salient parameters of these disputes are whether:

• a given pollutant affects all people or simply a genetically vulnerable set
• an effect is only specific to certain species
• an effect will only be apparent in the future and is presently negligible
• the threshhold for harm is present
• the pollutant is of direct harm or is a precursor
• employment or economic prosperity will suffer if the pollutant is abated

Blooms of algae and the resultant eutrophication of lakes and coastal ocean is considered pollution when it is caused by nutrients from industrial, agricultural, or residential runoff in either point source or nonpoint source form (see the article on eutrophication for more information). Heavy metals such as lead and mercury have a role in geochemical cycles and they occur naturally. These metals may also be mined and, depending on their processing, may be released disruptively in large concentrations into an environment they had previously been absent from. Just as the effect of anthropogenic release of these metals into the environment may be considered 'polluting', such pollution could also occur in some areas due to either autochthonous or historically 'natural' geochemical activity.

Carbon dioxide, while vital for the photosynthesis of plant life, is sometimes referred to as pollution, on the basis that raised levels of the gas in the atmosphere have and continue to adversely affect the Earth's climate. Such claims are disputed, particularly by political conservatives in Western countries. Due to this controversy, in many contexts carbon dioxide from such sources is qualiified neutrally under the label "emissions." See global warming for an extensive discussion of this topic. Disruption of the environment can also highlight the connection between areas of pollution that would normally be classified separately, such as those of water and air. Recent studies have investigated the potential for long-term rising levels of atmospheric carbon dioxide to cause slight but critical increases in the acidity of ocean waters, and the possible effects of this on marine ecosystems.