Filthy-looking blackheads feed the misconception that acne grows on grime. In reality, sebum turns the color of mud when exposed to air.

看上去脏乎乎的黑头粉刺让人们往往误解为粉刺就是在尘垢上长出来的。事实上，皮脂在暴露在空气中时会转变成泥土的颜色。

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The air pollution is a choking, filthy mess, and it is cutting years off of peoples' lives.

空气污染非常严重，空气脏乱，会使人的寿命减少好多年。

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Natural ventilation enters the wind from all around the outer wall place, then in the filthy room the air outward will pull out the wind using the stair hall watchtower chimney effect.

自然通风从四周外墙处进风，然后将污浊的室内空气利用楼梯间角楼的烟囱效应向外拔风。

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But the government is becoming increasingly concerned about the problems that pollution brings, such as sickness from filthy air and arid soil from acid rain, which has made it keen to boost the use of renewables and increase energy efficiency.

ECONOMIST: Anti-hero

Oliver Twist also highlights the rank poverty of the inner cities - particularly when the plot moves to Jacob's Island, " the filthiest, the strangest, the most extraordinary of the many localities that are hidden in London " where the houses were "so filthy, so confined, that the air would seem to be too tainted even for the dirt and squalor".

BBC: News Magazine

And I had the opportunity to go up in the air and see it a few times, and just filthy floodwater, because floodwater is filthy, as far as the eye could see.

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