The city's average concentration of PM2.5 was 28 micrograms per cubic meter during the period.

在此期间，北京PM2.5的平均浓度为每立方米28微克。

The average concentration of PM2.5 hazardous particles was 30 micrograms per cubic meter, down 9.1 percent year-on-year.

细颗粒物（PM2.5）平均浓度为 30 微克/立方米，同比下降 9.1%。

The city's average concentration of PM2.5 stood at 33 micrograms per cubic meter in the January to May period.

在 1 月至 5 月期间，北京的 PM2.5 平均浓度为每立方米 33 微克。

The average concentration of PM2.5 in Beijing is 33 micrograms per cubic meter in the first 11 months of this year.

今年前 11 个月，北京的 PM2.5 平均浓度为每立方米 33 微克。

The average concentration of the pollutants in the city fell by 9.5 percent year on year to 38 micrograms per cubic meter, the lowest since 2013.

全市污染物平均浓度同比下降9.5%，降至每立方米38微克，为2013年以来最低。

Data from China's Ministry of Ecology and Environment shows that the average concentration of PM2.5 in both Beijing and Zhangjiakou fell by over 50 percent year on year during the period.

中国生态环境部的数据显示，在此期间，北京和张家口的 PM2.5 平均浓度同比下降了 50% 以上。

The city's average concentration of PM2.5 was 33 micrograms per cubic meter in 2021, the lowest level since record-keeping began in 2013, Yu Jianhua, deputy director of the Beijing municipal ecology and environment bureau, said at a press briefing.

北京市生态环境局副局长余建华在新闻发布会上表示，2021 年，北京市 PM2.5 的平均浓度为 33 微克/立方米，是自 2013 年开始记录以来的最低水平。