Air pollution in Beijing reached a high level of 99 on the Air pollution Index on Friday as a sandstorm from the northwest shrouded the capital in dust, the China News Service reported.
据中国新闻社报道，北京市区13日遭遇了来自西北方的沙尘袭击，当天该市污染指数一度达到99。
2
Dust removal rate is an important index to measure the function of waste gas pollution treatment facilities.
除尘效率是衡量废气污染源治理设备性能的重要指标。
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Fly ash in flue gas not only crusts on the surface, stopping the dissolving of limestone, but also affects the dust discharge index, reducing the quality of gypsum.