영어 듣기 ,리스닝

Listen to part of a lecture in a public health class.

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I want to talk about a special form of air pollution today to be specific air pollution associated with coal. I'll start by outlining some specific details about coal, air pollution, and then we can move on to talk about what effects coal can have on human health. So, as all of you probably know, coal is a rock that can be burned to produce energy. These rocks, pieces of coal are mostly made out of carbon atoms. Yes, carbon, the very atom. That's such an important building block in our own bodies. But coal also contains small amounts of other elements in addition to carbon.

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Regarding air pollution. The most important of these elements are nitrogen and sulfur. burning coal, like burning many other fuels we've talked about releases carbon dioxide into the air, but burning coal also releases molecules called nitrogen oxides and sulfur dioxide, which present unique problems for public health.

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So I'll discuss them in detail now. I'll talk about nitrogen oxides. First, nitrogen oxides are released when coal is burned, like I previously mentioned. Right? And there are a couple of reasons why scientists are worried about nitrogen oxide emissions. The first reason is that in high concentrations, nitrogen oxides produce the brown smoke that can be seen covering several large cities in hot weather.

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The smog has been shown by many scientific studies to be associated with increased rates of respiratory illnesses. So you can see why the nitrogen oxides released by burning coal can have serious impacts on human communities. The burning of coal also releases sulfur dioxide. In fact, today, coal burning is the main process that releases sulfur dioxide in significant quantities into our atmosphere. Sulfur dioxide is an irritant similar to nitrogen oxides. And it is also one of the key components in creating acid rain, which has a decidedly negative effect on all kinds of plant life. Because our classes on public health and not ecology or botany, I won't go into too much detail on this. All you need to know about sulfur dioxide is that it acts as an irritant similar to nitrogen oxide. The moral of the story is, as you can imagine, there are very significant public health consequences to burning fuels like coal, which is why people have become increasingly worried about the rising prevalence of coal power plants in certain areas of the world.