It must be noted that sand is a 'particulate matter' (PM) and is recognized as such when measuring levels of the many different components that make up air pollution.

需要说明的是，沙子，是一种颗粒物质(PM)。测量空气污染物的不同组成成分含量等级时，它被归为颗粒物质。

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Our THP Series, temporary direct-fired make-up air heaters, are ideal for construction, drying, emergencies, special events, and military and disaster relief.

THP系列临时的补充空气加热器用于建筑、烘干、紧急事件、特殊时间以及军事和赈灾活动。

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More speed on the ground may make up for less in the air.

ECONOMIST: Air travel: After Concorde | The

High petrol prices and the desire to clean up our air quality make them the smart choice.

ENGADGET: UK's first fuel cell-powered black cab hits the streets of London

When Whirlpool set up factories to make refrigerators, air-conditioners, washing machines and microwave ovens in China in 1994, it assumed that it was racing against other foreigners.

ECONOMIST: Infatuation��s end