检测机构会检测直径小于10微米的微粒,即PM10浓度，并由此判定污染程度。

The safe limit for PM10 is set at 80 micrograms per cubic metre (mcg/m3), with levels in Paris Monday expected to be somewhere between 40 and 55 mcg/m3.
PM10 的安全水平线为每立方米80微克，周一巴黎PM10浓度预计介于40-55微克/立方米之间。

The city's alert level is fixed at 50 mcg/m3.
该市的PM10警戒水平为50微克/立方米。

According to a 2011 World Health Organisation report, the planet's most polluted city was Ahvaz in Iran with an average of 372 mcg/m3.
根据世界卫生组织2011年的报道，全球污染最重的城市为伊朗的阿瓦士，其微粒平均含量为372微克/立方米。

Beijing had an average of 121 mcg/m3, while Paris was measured at 38 mcg/m3.
北京市的PM10平均含量为121微克/立方米，而巴黎则是38微克/立方米。

Vocabulary

flout：蔑视，轻视

alternative：备选的，替代的

spike：剧增