4.Noise Pollution噪声汚染Obviously, a sudden loud noise could damage yourhearing, but what aboutthe constant hum of noisethat surrounds us every day? Spinning hard drives,passing cars, sirens in the distance, whirlingfans-it is almost impossible toescape noise pollution in the modern world. Every year, around 30millionAmericans are exposed to dangerous levels ofnoise as part of their job. Buteven people who don'texperience occupational noise hazards suffer fromsecondhand noise pollution. Hearing loss canlead to communication issues,discrimination, poorperformance at work and school, loneliness,anddepression.