Enviromental pollution

Sources and causes

 

Air pollution produced by ships may alter clouds, affecting global temperatures.

Air pollution comes from both natural and human-made (anthropogenic) sources. However, globally human-made pollutants from combustion, construction, mining, agriculture and warfare are increasingly significant in the air pollution equation.^[11]

Motor vehicle emissions are one of the leading causes of air pollution.^[12][13][14] China, United States, Russia, India^[15] Mexico, and Japan are the world leaders in air pollution emissions. Principal stationary pollution sources include chemical plants, coal-fired power plants, oil refineries,^[16] petrochemical plants, nuclear waste disposal activity, incinerators, large livestock farms (dairy cows, pigs, poultry, etc.), PVC factories, metals production factories, plastics factories, and other heavy industry. Agricultural air pollution comes from contemporary practices which include clear felling and burning of natural vegetation as well as spraying of pesticides and herbicides^[17]

About 400 million metric tons of hazardous wastes are generated each year.^[18] The United States alone produces about 250 million metric tons.^[19] Americans constitute less than 5% of the world's population, but produce roughly 25% of the world’s CO₂,^[20] and generate approximately 30% of world’s waste.^[21][22] In 2007, China has overtaken the United States as the world's biggest producer of CO₂,^[23] while still far behind based on per capita pollution - ranked 78th among the world's nations.^[24]

An industrial area, with a power plant, south of Yangzhou's downtown, China

In February 2007, a report by the Intergovernmental Panel on Climate Change (IPCC), representing the work of 2,500 scientists, economists, and policymakers from more than 120 countries, said that humans have been the primary cause of global warming since 1950. Humans have ways to cut greenhouse gas emissions and avoid the consequences of global warming, a major climate report concluded. But to change the climate, the transition from fossil fuels like coal and oil needs to occur within decades, according to the final report this year from the UN's Intergovernmental Panel on Climate Change (IPCC).^[25]

Some of the more common soil contaminants are chlorinated hydrocarbons (CFH), heavy metals (such as chromium, cadmium–found in rechargeable batteries, and lead–found in leadpaint, aviation fuel and still in some countries, gasoline), MTBE, zinc, arsenic and benzene. In 2001 a series of press reports culminating in a book called Fateful Harvest unveiled a widespread practice of recycling industrial byproducts into fertilizer, resulting in the contamination of the soil with various metals. 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 landfills that may have been subject to little control in the U.S. or EU. There have also been some unusual releases ofpolychlorinated dibenzodioxins, commonly called dioxins for simplicity, such as TCDD.^[26]

Pollution can also be the consequence of a natural disaster. For example, hurricanes often involve water contamination from sewage, andpetrochemical spills from ruptured boats or automobiles. Larger scale and environmental damage is not uncommon when coastal oil rigsor 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

Human health

Overview of main health effects on humans from some common types of pollution.^[27][28][29]

Adverse air quality can kill many organisms including humans. Ozone pollution can cause respiratory disease, cardiovascular disease, throatinflammation, chest pain, and congestion. Water pollution causes approximately 14,000 deaths per day, mostly due to contamination ofdrinking water by untreated sewage in developing countries. An estimated 500 million Indians have no access to a proper toilet,^[30][31]and 580 Indians die of water-related pollution every day.^[32] Nearly 500 million Chinese lack access to safe drinking water.^[33] A 2010 analysis estimated that 1.2 million people died prematurely in a year in Chinabecause of air pollution.^[34] In 2007 it was estimated that in India, air pollution is believed to cause 527,700 fatalities.^[35] Studies have estimated that the number of people killed annually in the US could be over 50,000.^[36]

Oil spills can cause skin irritations and rashes. Noise pollution induceshearing loss, high blood pressure, stress, and sleep disturbance.Mercury has been linked to developmental deficits in children andneurologic symptoms. Older people are majorly exposed to diseases induced by air pollution. Those with heart or lung disorders are at additional risk. Children and infants are also at serious risk. Lead and other heavy metals have been shown to cause neurological problems. Chemical and radioactive substances can cause cancer and as well as birth defects.

Environment

Pollution has been found to be present widely in the environment. There are a number of effects of this:

·         Biomagnification describes situations where toxins (such as heavy metals) may pass through trophic levels, becoming exponentially more concentrated in the process.

·         Carbon dioxide emissions cause ocean acidification, the ongoing decrease in the pH of the Earth's oceans as CO₂ becomes dissolved.

·         The emission of greenhouse gases leads to global warming which affects ecosystems in many ways.

·         Invasive species can out compete native species and reduce biodiversity. Invasive plants can contribute debris and biomolecules (allelopathy) that can alter soil and chemical compositions of an environment, often reducing native species competitiveness.

·         Nitrogen oxides are removed from the air by rain and fertilise land which can change the species composition of ecosystems.

·         Smog and haze can reduce the amount of sunlight received by plants to carry out photosynthesis and leads to the production oftropospheric ozone which damages plants.

·         Soil can become infertile and unsuitable for plants. This will affect other organisms in the food web.

·         Sulfur dioxide and nitrogen oxides can cause acid rain which lowers the pH value of soil.

Environmental health information

The Toxicology and Environmental Health Information Program (TEHIP)^[37] at the United States National Library of Medicine (NLM) maintains a comprehensive toxicology and environmental health web site that includes access to resources produced by TEHIP and by other government agencies and organizations. This web site includes links to databases, bibliographies, tutorials, and other scientific and consumer-oriented resources. TEHIP also is responsible for the Toxicology Data Network (TOXNET)^[38] an integrated system of toxicology and environmental health databases that are available free of charge on the web.

TOXMAP is a Geographic Information System (GIS) that is part of TOXNET. TOXMAP uses maps of the United States to help users visually explore data from the United States Environmental Protection Agency's (EPA) Toxics Release Inventory and Superfund Basic Research Programs.