การฟัง TOEFL

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Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about a surprising source of pollution: common household products. Many people assume that outdoor air pollution is the main threat, but in fact, indoor air can be two to five times more polluted than outdoor air. This is partly because of volatile organic compounds, or VOCs, which are emitted as gases from certain solids and liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Now, you might think of paints and varnishes, but did you know that even air fresheners and cleaning supplies can release VOCs? The irony is that products designed to make our homes smell fresh can contribute to poor indoor air quality. So what can we do? One solution is to increase ventilation by opening windows and using exhaust fans. Another is to choose products labeled 'low-VOC' or 'no-VOC'. Also, it's important to follow the manufacturer's instructions and store these products properly. The key is to be mindful that our indoor environment is just as important as the outdoors.