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1.The air quality index is a cumulative dust index that measures the amount of particulate matter in the air.
空气质量指数是一个累积粉尘指数，它衡量空气中颗粒物的含量。
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2. The cumulative dust index has been rising steadily since the beginning of the year, indicating an increase in pollution levels.
自年初以来，累积粉尘指数一直在稳步上升，表明污染水平有所增加。
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3. The cumulative dust index is closely monitored by environmental agencies to ensure that air quality remains safefor public health.
环境机构密切监测累积粉尘指数，以确保空气质量对公众健康安全。