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1. The background concentration of the pollutant is high, which may affect the health of the people livingin the area.
污染物的背景浓度很高，这可能会影响该地区居民的健康。
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2.The background concentration of carbon dioxide in the atmosphere is a key factor in determining the global warming effect.
大气中二氧化碳的背景浓度是决定全球变暖效应的关键因素。
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3.The background concentration of methane gas in the atmosphere is also an important indicator of the environmental quality.
大气中甲烷气体的背景浓度也是衡量环境质量的一个重要指标。