New Delhi: Delhi is the most polluted city in the world when it comes to air quality, a WHO study released today says.
The 2014 release of the Ambient Air Pollution (AAP) database contains results of outdoor air pollution monitoring from almost 1600 cities in 91 countries.
The national capital has the highest concentration of PM2.5 -- particulate matter less than 2.5 microns -- form of air pollution, which is considered most serious.
This form of concentration consists of tiny particles that puts people at additional risk of respiratory diseases and other health problems, the World Health Organisation said.
The situation is so bad in Delhi that its air has PM2.5 concentrations of 153 micrograms and PM10 concentrations of 286 micrograms--much more than permissible limits.
In comparison, Beijing, which was once considered one of the most polluted cities, has PM2.5 concentration of 56 micrograms and PM10 concentration of 121 micrograms.
Air quality is represented by annual mean concentration of fine particulate matter (PM10 and PM2.5,-- particles smaller than 10 or 2.5 microns).
The database covers the period from 2008 to 2013, with the majority of values for the years 2011 and 2012.