Air pollution is a major issue in Sarajevo. According to the 2016  World Health Organization's Ambient Air Pollution Database, the annual average PM2.5 concentration in 2010 was estimated to be 30 μg/m3 based on PM10 measurement, which is 3 times higher than recommended by  WHO Air Quality Guidelines for the annual average PM2.5. There are no recent direct long-term PM2.5 measurements available in Sarajevo and only estimates can be made from PM10, which is the less health-relevant than PM2.5. Real-time air quality data in the form of PM10, ozone, NO2, CO and SO2 by the  Federal Hydrometeorological Institute .