最近，首都北京屡屡遭遇大雾天气，空气能见度降低，交通运输以及市民生活受到严重影响，更重要的是，衡量空气质量的重要指标PM2.5再创新高，短时达到重度污染程度，市民健康状况堪忧。

The heavy smog and haze that shrouded（笼罩） Beijing recently pushed the pollution index to a record high， becoming increasingly popular with media across the country. Meanwhile， many other cities also witnessed smoggy weather. On Saturday， levels of PM2.5 passed 300 micrograms per cubic meter in 33 of the 74 cities. Face mask sales surged and hospitals crowded with sick people in cities across the country.

PM2.5 refers to particulate matter 2.5 microns or less in diameter（直径小于或等于2.5微米的颗粒物质）and these matters are believed to pose greater health risks than larger particles because they can embed deep in peoples lungs. The growth and severity of PM2.5 pollution in recent years is directly related to the rapid rise in coal consumption， allied to an increase in vehicle exhaust emissions （废气排放）. Under these circumstances， better city management and environmental protection are at urgent need for public health is at risk.

（Roger 整理）