The Air Quality Index runs from zero to 500, with 500 being the most unhealthy.

空气质量指数的范围从0到500，上限500表示空气质量最不健康。

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One of the main quality index of polyether is the potassium and sodium contents.

聚醚中钾、钠含量是其重要质量指标之一。

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The riding quality index evaluating model is established according to field test result.

根据现场试验结果，建立了行驶舒适性指数评价模型。

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Dr.Kausalya Pendyal tells her patients in Richmond, Virginia before they go outside to check the Air Quality Index - a U.S.government assessment of pollutants in the air.

VOA: standard.2010.08.04

The government's Air Quality Index shows "unhealthy" pollution levels in much of Southern California.

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But as a search engine, we can do what we think is best to return a high quality index.

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An unofficial reading from the US embassy's air quality index recorded over 500 early in the morning, but changed to 168 as of 13:00 (05:00 GMT).

BBC: Smog and sandstorm engulf China's capital