Air pollution is the introduction of chemicals, particulate matter, or microscopic organisms into the atmosphere; in particular, when concentrations of those substances cause adverse metabolic change to humans or other species. The most common and widespread air pollutants include carbon monoxide, sulfur dioxide, nitrogen oxides and particulate matter.
Presently, the greatest occurrences of air pollution are in China, India, Indonesia, South Africa, Brazil, Mexico and Argentina. Each year air pollution is the cause of millions of human deaths, and even larger numbers of respiratory, circulatory, and cancer-related disease occurrences. Also, indoor air pollution is a significant source of human death and disease—mortality and morbidity—through indoor burning of wood and charcoal (especially in developing countries), tobacco smoking, radon trapping and a host of chemical substances found in paints, printing supplies and cleaning products.
An increase of natural background concentrations to concentrations of a few micrograms per cubic meter of such common pollutants as sulfur dioxide, nitrogen oxides and ammonia may produce, for instance, increased growth of forests; however, higher levels of these chemicals produce such adverse effects on forests as decreased growth, greater susceptibility to diseases and pests, and ultimately to forest die-back.
Indoor air pollution refers to the occurrence of contaminants within a home, workplace (or other inhabited enclosure) arising from such sources as fuel combustion...
UrbanizationLast Updated on 2014-06-29 18:43:46Urbanization refers to a process whereby the building intensity of a high density human population increases or the number of people living in an urban area increase. Globally, this process has been on the rise for centuries; however, it has accelerated since the Industrial Revolution and was boosted again especially during the second half of the 20th century. The urbanization process was fueled mainly by migration from rural areas. The process usually comes to its end when urban population reaches a level of 80 to 90 percent of the total population of a country. Most developed countries reached this stage during the 20th century. Currently, at the beginning of the 21st century, urbanization is on the rise in most developing and less developed countries (Figure 1).
Despite the fact that the urbanization process in any country may come to a leveling off, the growth of urban population... More »
PollutionLast Updated on 2014-06-28 18:51:13Pollution is environmental contamination that results in harm or death to living organisms. Most pollution is in the form of chemical additions to air, water or soil; however, in modern times starting in the mid-twentieth century noise and light have been considered as pollution sources. Most pollution is man-made, with natural fluctuations in atmospheric composition, surface water bodies and soil considered temporal gyrations in the Earth's natural history. The chief driver of pollution is the massive growth in human population, which induces the proximate causes of intensive agriculture and extraordinary industrial output. The United Nations and the Blacksmith Institute are two prominent organisations that tabulate locales of the greatest pollution intensity; while their listings do not correspond precisely, the overlap countries that both entities agree are the worst polluted... More »
Lifestyle, technology and CO2 emissions in ChinaLast Updated on 2014-06-28 17:59:40
China as the world’s largest developing country and the most populous country has achieved notable success in developing their economy with approximate 10 percent average annual growth of GDP over the last two decades [1-3]. Large sections of the population have been experiencing a transition from ‘poverty’ to ‘adequate food and clothing’; today growing parts of the population are getting closer to ‘well to do’ lifestyles . However, the rapid growth of the economy has not only lead to dramatic changes of wealth and people’s lifestyle, but has also caused a huge amount of resources and energy consumption and associated CO2 and other emissions creating serious environmental problems on both local, regional and global scales [4-6]. Between 1990 and 2004 China’s total energy consumption has grown 5.0% annually from... More »
Earth's atmospheric airLast Updated on 2014-04-02 14:56:48The Earth's atmospheric air is a colorless, odorless and tasteless mixture of gases consisting mostly of nitrogen (N2) and oxygen (O2). It is the part of Earth's atmosphere that humans and all other animals breathe in order to obtain the oxygen needed to sustain life.
The Earth's atmosphere not only contains the air we breathe, it also holds clouds of moisture (water vapor) that become the water we drink. Furthermore, it protects us from meteors and harmful solar radiation and warms the Earth's surface by heat retention. In effect, the atmosphere is an envelope that protects all life on Earth.
The air may contain pollutants that originate from a variety of sources such as our industries and our vehicles, and can directly or indirectly affect our health and the natural environment. These effects may be experienced near the sources of air pollution and some air... More »
RespirationLast Updated on 2014-01-31 16:43:42Respiration is the gas exchange effected by living organisms for the purpose of sustaining vital metabolic processes. In the case of most animals, oxygen is taken into the organism, and carbon dioxide is expelled. In the case of plants, the inverse process occurs of consuming carbon dioxide and expelling oxygen as a waste gas.
Respiration may also be viewed at a cellular level, examining gas exchange at the cell wall; for very simple organisms, such as unicellular lifeforms, the process of gas exchange with the environment is simplified, so that cellular wall gas exchange is the totality of respiration for such an organism.
In the case of some bacteria and archaea, respiration sometimes occurs without any oxygen, and alternative molecular gases such as hydrogen sulfide or methane may participate in respiration and subsequent cellular metabolic reactions. Often such organisms are... More »
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