On 22nd September 2021, the World Health Organization released the so long-awaited update of the Air Quality Guidelines (AQGs). They are bold and ambitious but will governments adopt them?
Let’s see how the updated AQGs compare to the old ones, which were released in 2005. The classical pollutants (Particulate Matter PM2.5/10, and NO2) have been reduced significantly. They have introduced additional AQG levels, such as for peak season Ozone (O3), 24-hour averaging time for Nitrogen Dioxide (NO2), and Carbon Monoxide (CO). On the contrary, they have increased the Sulfur Dioxide (SO2) levels from 20 μg/m3 to 40 μg/m3.
See The Air 