In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.

在《清洁空气法案》强制要求美国使用无铅气体的二十年里，铅在世界范围内的累积量显著下降。

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Lead weights and air cylinders encumbered the divers as they walked to the shore.

当潜水员们走向海岸时，铅坠和氧气缸让他们步履维艰。

《柯林斯英汉双解大词典》

Lead in air, mercury in food and other chemicals can result in long-term, often irreversible effects, such as infertility, miscarriage, and birth defects.

空气中的铅、食品中的汞和其它化学品可造成长期并且通常不可逆转的结果，例如不孕症、流产和出生缺陷。

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But what problems might the presence of Russian-manned air defences lead to?

BBC: Diplomatic correspondent

The authors say a higher limit could increase gas emissions and air pollution and could lead to increased obesity, with more people taking advantage of shorter car journeys.

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Critics, however, say the mining operation will destroy forests in the area, contaminate groundwater and pollute the air with chemical substances like lead, mercury and arsenic.

BBC: Arsonists attack Hellas gold mine in northern Greece