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Pollution is any contamination of the natural environment, and includes air pollution, water pollution, soil contamination, noise pollution, littering and radioactive contamination. Pollution affects everybody, whether it be through the emission of greenhouse gases that contribute to climate change or through the direct poisoning of the natural environment on which a local community depends. The World Heath Organization, in conjunction with the World Bank, estimates that 20 percent of deaths in the developing world are directly attributed to environmental factors from pollution.[1]

Greenhouse Gases

Greenhouse gases are gases in the earth’s atmosphere that form a layer around the earth, trapping heat and creating what is known as the greenhouse effect. The main greenhouse gases are water vapour, carbon dioxide, methane, nitrous oxide, ozone and chloroflurocarbons (CFCs). The average temperature of the earth’s surface has risen by 0.74 degrees C since the late 1800s. It is expected to increase by another 1.8° C to 4° C by the year 2100, which would be the most drastic change in the earth’s temperature in more than 10,000 years.[2] The principal reason for this is the human impact of industrialisation – the burning of fossil fuels and the cutting down of forests.

Light Pollution

While electric lights are not seen as inherently bad, as it can have great benefits for society; to extend the length of the productive day, and offer more time to work and recreational activities that require light. The definition of light pollution is “when artificial outdoor lighting becomes inefficient, annoying, and unnecessary. Many environmentalists, as well as medical researchers consider light pollution to be one of the fastest growing and most pervasive forms of environmental pollution. A growing body of scientific research suggests that light pollution can have lasting and adverse effects on both human and wildlife health.

The International Astronomical Union set the threshold for “light-polluted status” at if the artificial sky brightness is greater than 10% of the natural sky brightness above 45° of elevation. According to these terms, 99% of the European Union and the United States (excluding Alaska and Hawaii) live in areas beyond this threshold.

Light pollution has also long been known to affect both flora and fauna. Prolonged exposure to artificial lights may prevent trees from adjusting to season variations properly, affecting the behaviours and breeding cycles of the wildlife that depend on these trees for their natural habitat.[3]

For humans, when light pollution causes light photons to hit the retina during times of rest, it can disrupt our natural circadian rhythm. Studies on mice have shown that this disruption can cause increased weight gain, slowed metabolism, and difficulty in learning new tasks. All effects were in line with the prefrontal cortex, the area of the brain linked to learning, adaptation, and emotional control.[4]


Help build an interactive global map of light pollution at night with the Globe at Night web app.

Pollution and Progress

The Kyoto Protocol sets binding targets for 37 industrialized countries and the European community for reducing greenhouse gas (GHG) emissions .These amount to an average of five per cent against 1990 levels over the five-year period 2008-2012. The United Nations Framework Convention on Climate Change is an international treaty signed by 192 countries that sets general goals and rules for confronting climate change. An international meeting, the Conference of the Parties, took place in December 2009 to review progress on climate change and set new targets for post-Kyoto.

Studies and Initiatives

The Blacksmith Institute publishes and annual survey on the world’s worst pollution problems and the world’s most polluted places.

UK Data Service case study: Low emission European energy scenarios by Mark Barrett, University College London.

Environmental progress blogs

See also


  1. http://www.blacksmithinstitute.org/our-strategy.html
  2. http://unfccc.int/essential_background/feeling_the_heat/items/2917.php
  3. Chepesiuk R 2009. Missing the Dark: Health Effects of Light Pollution. Environ Health Perspect 117:A20-A27. doi:10.1289/ehp.117-a20
  4. http://www.geekosystem.com/circadian-rhythm-fat/


United Nations Environment Program

US Environmental Protection Agency

World Wildlife Fund


Blacksmith Institute

Page created by —Sarahgregory 15:41, 11 June 2009 (UTC)