The World Health Organisation's (WHO) urban air quality database report has revealed that Delhi is no more the most polluted city in the world. Among 3,000 cities across 103 countries, Delhi ranks 11th now in terms of PM 2.5 (fine, particulate pollution) and stands 25th in PM 10 (coarse pollution particles) levels.

As per the latest database, the most polluted city in the world is Zabol in Iran. Four cities of India are among the ten most polluted cities in the world. They are Gwalior, Allahabad, Patna and Raipur.

An expert said, "To get a more accurate and balanced picture of air quality globally, WHO should have taken NOx in to account too. NOx levels are in high in many parts of Europe too."

Data from several research and government organizations was used by WHO for the database. The report said, “the database, is based on ground measurements of annual mean concentrations of particulate matter (PM 10 and PM 2.5) and aims at representing an average for the city or town as a whole, rather than for individual stations. Years of measurements range from 2010 to 2015, unless the latest available data was older."

Experts believed that efforts made by Delhi could have helped for the improvement. WHO's Dr Carlos Dora opined that, it is important to make the urban air quality a development and health priority by the city and national governments.

"When air quality improves, health costs from air pollution-related diseases shrink, worker productivity expands and life expectancy grows. Reducing air pollution also brings an added climate bonus, which can become a part of countries' commitments to the climate treaty," Dr Carlos Dora added.

A road map would be discussed by member states during the World Health Assembly happening between 24 May 2016 and 30 May 2016, for an enhanced global response to deal with adverse health effects caused by the air pollution.

- Sumana