EMT 307- Environmental Pollution

Air pollution can be high in parts of North America and Europe, but it has improved slightly over the past decade with new environmental regulations and progress in technology. Meanwhile, China and India have been frequently cited as areas where air pollution is at its worst. In some cities in Asia, it has exceeded 20 times the World Health Organization (WHO) guidelines. Nevertheless, there is considerable variation within those countries both regionally and locally, especially in recent years. In Beijing, for example, latest estimates show an improvement compared to previous years. In fact, data from WHO (2016) unveil a striking new analysis: the most polluted city in the world (by PM10 measurements) is Onitsha, Nigeria. Two other Nigerian cities, Kaduna and Aba, are also among the top 10 most polluted cities. Zabol, Iran, is the most polluted city by PM2.5 measurements. Asian cities continue to occupy the majority of the top of the list for PM2.5 measurements. 3.2 Indoor Air Pollution Burning of solid fuels for household cooking, heating and lighting is a major cause of household, or indoor, air pollution. Indoor air pollution puts nearly 3 billion people worldwide at risk of ill health and early death. Indoor pollutants include particulate matter (PM10 and PM2.5), mould, dust mites and bacteria, as well as chemicals and Volatile Organic Compounds (VOCs) [such as formaldehyde and benzene] from paints, personal care products and building materials. The effects of indoor air pollution kill more children globally than outdoor air pollution, especially in Africa and Asia. Eighteen of the nineteen countries where 95 per cent or more of the population use solid fuels for cooking are in sub-Saharan Africa. 3.3 Criteria Pollutants Clean, dry air consists primarily of nitrogen and oxygen, 78 percent and 21 percent respectively, by volume. The remaining 1 percent is a mixture of other gases, mostly argon (0.9 percent), along with trace (very small) amounts of carbon dioxide, methane, hydrogen, helium, and more. Water vapour is also a normal, though quite variable, component of the atmosphere, normally ranging from 0.01 to 4 percent by volume; under very humid conditions the moisture content of air may be as high as 5 percent. The gaseous air pollutants of primary concern in urban settings include sulfur dioxide, nitrogen dioxide, and carbon monoxide; these are emitted directly into the air from fossil fuels such as fuel oil, gasoline, and natural gas that are burned in power plants, automobiles, and other combustion sources. Ozone (a key component of smog) is also a gaseous pollutant; it forms in the atmosphere via complex chemical reactions occurring between nitrogen dioxide and various volatile organic compounds (e.g., gasoline vapours). Airborne suspensions of extremely small solid or liquid particles called ―particulates‖ (e.g., soot, dust, smokes, fumes, mists), especially those less than 10 micrometres (μm; millionths of a metre) in size, are significant air pollutants because of their very harmful effects on human health. They are emitted by various industrial processes, coal- or oil-burning power plants,