The new Global Urban Ambient Air Pollution Database of the World Health Organization (WHO) released Thursday puts Delhi at 11th position, much better than 2015 when it was the number one. The most polluted city this year is Zabol in Iran.

The WHO released data on levels of particulate matter in 3,000 urban areas in 103 countries highlighting that air pollution is responsible for more than three million premature deaths worldwide every year. More than 80 per cent of people living in urban areas - where air pollution is monitored - are exposed to air quality levels that exceed WHO limits.

While all regions in the world are affected, populations in low-income cities are the worst hit. According to the latest urban air quality database, 98 per cent of cities in low and middle income countries with more than 100,000 inhabitants do not meet WHO air quality guidelines.

However, in high-income countries, the percentage decreases to 56 per cent. The WHO standards for PM 2.5 are 10 micrograms per cubic metre. The numbers of cities not meeting the standards globally have increased over time from 1,122 in 2014 to 2,051 cities this year.

Four Indian cities, Patna, Allahabad, Gwalior and Kanpur, find place among the top 10 polluted cities. The annual average PM2.5 levels in Delhi have reduced by 20 per cent since 2014.

“Air pollution is a major cause of disease and death. It is good news that more cities are stepping up to monitor air quality, so when they take actions to improve it, they have a benchmark. When dirty air blankets our cities, the most vulnerable urban populations - the youngest, oldest and poorest - are the most impacted,” says Dr Flavia Bustreo, WHO Assistant-Director General, Family, Women and Children’s Health.

The Biggest Killer

According to the Centre for Science and Environment, it is disturbing that several Indian cities — in fact smaller cities — have shown substantial increase in pollution levels since 2014.