tailieunhanh - Health and the Environment: Water Pollution

Many studies have been carried out in different parts of the world to try to gain a better understanding of personal exposure to air pollutants while commuting by different modes [5-8], aided by the recent development of portable air quality monitoring technology. Although the results from such studies are frequently complex and sometimes contradictory due to a large number of confounding factors [9], typically they show that the mean concentrations of air pollutants pedestrians and cyclists are exposed to are lower than those experienced by car drivers and bus passengers [10,11]. It is believed that this is due to. | Health and the Environment Water Pollution Seen Environmental Learning Information Sheet no 5 The importance of water The earth s surface is 75 water but out of this only 3 is fresh water of which only 1 is available for people to use. Water sustains life for humans animals and plants. People need water for basic everyday activities like drinking and cooking but water is also very important for the fuelling of agriculture and industry and plays an important role in the nature of national economies. However the supply of freshwater available to humanity is shrinking. One of the main causes of this is the polluting of many freshwater resources. In some countries lakes and rivers have become polluted with an assortment of waste including untreated or partially treated municipal sewage toxic industrial effluents harmful chemicals and ground waters from agricultural activities. Polluted water supplies not only limit water availability but also put millions at risk of water-related diseases. The lack of freshwater is likely to be one of the most critical natural resource issues facing people in the next 50 years. The world s population is expanding rapidly yet our supplies of freshwater are not placing greater demand on our water resources. This makes it even more important that the remaining freshwater we have is kept safe and clean. Pollution problem Pollution is everywhere. Few countries have adequately safeguarded water quality and controlled water pollution. Many countries do not have standards to control water pollution adequately while others cannot enforce water quality standards. The consequence of having polluted water is A reduction in water quality which leads to health problems The endangerment of agriculture and aquatic ecosystems. Water pollution occurs when a body of water is affected with large amounts of harmful substances. When water is considered unfit for its intended use it is called polluted. There are two types of water pollutants point source and