Pollution inequality between the world’s rich and poor is widening, according to the latest global data from the World Health Organisation (WHO) which shows that 7 million people – mostly in developing nations – die every year from airborne contaminants.

Overall, nine in 10 people on the planet live with poor, even dangerous, air, says the WHO report, which is considered the most comprehensive collection of global air quality data. But levels of contamination vary widely depending on government actions and financial resources.

For the first time, the report included regional historic data, which showed that more than 57% of cities in the Americas and more than 61% of cities in Europe had seen a fall in PM10 and PM2.5 particulate matter between 2010 and 2016.

But these gains were set against a worsening trend in other regions.

The most rapid deterioration was in south and south-east Asia, where more than 70% of poor cities suffered worsening air quality. The Middle East was also badly affected.

Delhi and Cairo are by far the most polluted mega-cities in the world with average PM10 levels more than 10 times the WHO guidelines. They are followed by Dhaka, Mumbai and Beijing, each with particulate concentrations about five times the recommended level.

The Americas, principally the US and Canada, was the only region where a sizeable majority of people – 80% – breathe air that meets WHO guidelines on particulates. In Asia and the Middle East, the figure was close to zero.

In terms of household air pollution, which contributed to 3.8m deaths, the gap is also wide because families in poorer nations are more dependent on burning wood, coal and kerosene for cooking and heating.

Overall, the authors said the global annual death toll of 7 million is largely unchanged from the previous 2016 air pollution report by the WHO, despite growing awareness of the problem and government promises of action.

Read more at the Guardian