SHANGHAI, (Reuters) – Not a country met the World Health Organization (WHO), air quality standard for 2021. A Tuesday survey of pollution data from 6,475 cities revealed that smog has rebounded in certain regions following a COVID-related drop.

Following a change in its guidelines, last year the WHO recommended that annual average readings of PM2.5 (small and dangerous airborne particles) should not exceed 5 micrograms/cubic metre.

According to data compiled by IQAir (a Swiss company monitoring air quality), only 3.4% of the surveyed towns met this standard for 2021. As high as 93 cities had PM2.5 levels that were at least 10 times the level recommended.

Christi Schroeder (IQAir’s air quality science manager), stated that there are many countries making significant progress in reducing emissions. China began with very large numbers. They are now decreasing. It is also getting worse in some places around the globe.

According to data, India’s pollution has worsened over the past 2021. New Delhi was the worst-polluted capital in the world. The most polluted nation was Bangladesh, which was unchanged over the year before, and Chad was ranked second, after data from an African country was added for the first-time.

China’s pollution war has been ongoing since 2014. China fell 22nd on the PM2.5 rankings for 2021. This is down from the 14th position a year prior. Average readings have improved slightly in recent years to 32.6 micrograms according to IQAir.

Hotan was located in the northern region of Xinjiang. The average PM2.5 reading was more than 100 micrograms.

Following being defeated by Ghaziabad (both in India) and Bhiwadi it fell to 3rd on the World’s Most Polluted Cities List.