This can be really dangerous because there are harmful chemicals in the smoke from both wood and coal and they can seriously pollute the air in your home.

这是非常危险的，因为木材和煤炭产生的烟雾中都含有有害的化学物质，会严重污染家里的空气。

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Factories that burn coal still polluted the air with a lot of black smoke.

烧煤的工厂仍然产生大量的黑烟污染空气。

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Smoke stacks are seen at a coal power plant in West Virginia.

图中所见为西弗吉尼亚州燃煤电厂的烟囱。

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It is bliss to breathe in clean, fresh air with no coal smoke and no dust.

NPR: Part One

Coal ash is captured before it can escape at a smoke stack into the air, it's channeled into ponds near the river and contained there by earthen dikes.

NPR: In Tenn. Town, A Muddy Christmas For Some

Furnaces could no longer emit "dark smoke" and households were offered grants towards the cost of converting their coal-burning grates to smokeless fuel.

BBC: News, London