ADB_book_18 April.qxp - Himalayan Document Centre - icimod

Chapter 7Air Pollution and ClimateChangeIntroductionPeople can live without food and water for days,but cannot survive without air for even a fewmoments. An average person needs 13.5 kg ofair every day. Dry air has concentrations of certaingases that are naturally present in the atmosphere.Any disturbance to the balance of the naturalcomposition of air that has an adverse effect onpeople or the environment can be termed airpollution.In pursuit of rapid economic development,many developing countries are confronted withenvironmental problems due to increasing airpollution resulting from industrialization, urbanization,and motorization. Worldwide, the World HealthOrganization (WHO) estimates that as many as 1.4billion urban residents breathe air with pollutantconcentrations exceeding the WHO air guidelinevalues (WRI 1998). Although the causes andconsequences of air pollution are often localized,transboundary movement of air pollutants hasregional as well as global implications. Aciddeposition, global climate change, and stratosphericozone depletion are among the emerging issues thattranscend political boundaries. Air pollution can bean ongoing feature, but can also present in acute,sometimes catastrophic, episodes. Table 7.1 showssome major air pollution disasters that haveoccurred during the last century.Usually air pollution is differentiated into threebroad categories: ambient, indoor, and transboundary.Ambient air refers to the air close to the groundthat is in direct contact with the living world; indoorair pollution refers specifically to air within buildings,whether at the workplace or in the home; andtransboundary air pollution is used to refer topollutants that have entered the upper atmosphereand travel far from their source.Air pollution of all three types is strongly affectedby climate—precipitation, wind, temperature,radiation—and thus by changes in climate or“climate change”. At the same time, air pollution isthought to be one of the major contributors to thepresent situation of “climate change”This chapter deals with air pollution, its status,sources, and impacts, together with the context ofthe climate in Nepal and possible effects of climatechange.Status and Trends of Ambient AirPollution in NepalAmbient air pollution may derive from both naturaland anthropogenic sources. A typical natural processTable 7.1: Catastrophic Air Pollution EpisodesYearLocation1930 Meuse Valley,Belgium1948 Donora,PennsylvaniaDeaths and/orInjuries63 deaths600 sick20 deaths6,000 sickCausePollutants released by coke ovens, steel mills, blast furnaces , zinc smelters, glassfactories, and sulfuric acid plan ts were trapped in the valley.Effluents from industries like a sulfuric acid plant, steel mill, and zinc productionplant, became trapped in a valley by a temperature inversion and produced anunbreathable m ixture of fog and pollution (smog).1952 London, England 4,000 deaths “The London Fog” , daily temperatures below average, and industrial pollutantscombined with condensation in the air to form a dense fog. Concentrations ofpollutants reached very high levels causing suffocation and death.1984 Bhopal, India 20,000 deaths120,000 injuredSource: Compiled from various sources by MENRIS staffGas leakage from the Union Carbide pesticide plant caused a toxic cloud to driftover the city.Chapter 7: Air Pollution and Climate Change81