Indoor pollution, which includes sources like home heating and cooking, has remained constant over the past several decades despite advances in the area.

在过去几十年中，来源于诸如家庭供暖和烹饪等的室内污染持续存在，尽管在这方面已经有所改进。

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Moreover, during the past two decades, China has used pollution charges and other measures to keep both air and water pollution levels constant even as economic output has doubled.

中国在过去20年利用污染收费制和其他措施，在经济产出增长一倍的情况下使空气和水污染问题没有进一步恶化。

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They make a constant din and cause acute pollution.

这些摩托车喧嚣不断，还会造成严重污染。

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Engineers have found that wetlands, grassy fields and soil or sand filters can take in stormwater with different levels of pollution and release water with a relatively constant cleanliness.

VOA: standard.2010.08.04

But speaker systems to date have annoyed everyone, employees especially, with their constant, ubiquitous noise pollution.

FORBES: Magazine Article

We can and should control surface pollution as that effects air quality yet there is a huge difference between controlling air quality as that remains constant in cold or warm environments while temperatures constantly fluctuate from day to night, month to month and year to year, in the Western isles of Europe we are having a particularly cool and wet summer.

FORBES: Good News For Polar Bears Is Bad News for Global Warming Alarmists