This document describes the latest WHO database on ambient air quality. Since 2011, WHO has been compiling and publishing ground measurements of air quality and, specifically, the annual mean concentrations of particulate matter with a diameter ≤ 2.5 μm (PM2.5) and ≤ 10 μm (PM10).

链接地址：https://iris.who.int/bitstream/handle/10665/368432/9789240047693-eng.pdf?sequence=1&isAllowed=y