It’s estimated that two million people worldwide die from air pollution every year, the World Health Organization (WHO) said Monday, Xinhua reported.

Elevated levels of fine particle pollution, which could cause heart disease, lung cancer, asthma and acute lower respiratory infections, are common in many urban areas. Some cities register fine particle pollution levels which are 15 times higher than WHO guidelines.

WHO has studied publicly-available air quality data from almost 1100 cities across 91 countries, including capital cities and cities with populations of more than 100,000 people. The data used are based on measurements taken from 2003 to 2010, with most being reported for the period 2008-2009.