According to the 2023 World Air Quality Report released by IQAir, a Swiss air monitoring body, Nagaland’s Capital Kohima is the 465th Most Polluted City in 2023 out of 7812 cities in the world. The report says that the PM2.5 annual average in Kohima was 33.9 micrograms per cubic metre.

The World Health Organization (WHO) recommends the annual mean concentrates of PM2.5 not exceeding 5 µg/m3. PM2.5 is the fine inhalable particles with diameters that are generally 2.5 micrometers and smaller which can increase the risk of health problems.

As per the 2023 World Air Quality Report, the air in Kohima exceeds the PM2.5 limit by 5 to 7 times.

Overall, India has been named the third most polluted country with 54.4 µg/m3, more than 10 times higher than the WHO PM2.5 annual guideline. Bangladesh is at the first position with 79.9 µg/m3, while Pakistan with 73.7 µg/m3, comes second.

IQAir says that the data utilized to create the report was aggregated from the global distribution of more than 30,000 regulatory air quality monitoring stations and low-cost air quality sensors operated by research institutions, governmental bodies, universities and educational facilities, non-profit non-governmental organizations, private companies, and citizen scientists.

Only seven countries met the WHO annual PM2.5 guideline – Australia, Estonia, Finland, Grenada, Iceland, Mauritius, and New Zealand – while 124 (92.5%) out of 134 countries and regions exceeded 5 µg/m3.

Except for eight countries, the top 50 most polluted cities in the world list is dominated by Indian cities. Begusarai in Bihar is the most polluted city with 118.9 µg/m3. Assam’s Guwahati is second with 105.4 µg/m3 while Delhi comes third with 102.1 µg/m3. The top 132 cities all exceed WHO guidelines by over 10 times.