Top 10 most polluted cities (2016)
In measuring air quality particles of a PM2.5 size are collected - around one-30th the size of human hair. Larger particles can also be measured - PM10 particles are coarser and can still be inhaled leading to health hazards. The table below is based on the WHO's PM2.5 data. The WHO recommends 10 micrograms per cubic metre of PM2.5 as a guideline level for safe air.
|City||PM 2.5 Annual Mean Microgrammes per Cubic Metres µg/m3|
|Riyadh, Saudi Arabia||156|
|Al Jubail, Saudi Arabia||152|
Source: World Bank