Nigeria, March 25 -- The World Health Organisation (WHO) has warned that air pollution remains one of the most severe global health threats, contributing to around 7 million premature deaths annually.

In a report posted on its X handle on Tuesday, the health body noted that 99 per cent of the world's population breathes air that exceeds its guideline limits.

It said low and middle-income countries are experiencing the highest levels of exposure.

The polluted air contains harmful substances such as particulate matter, carbon monoxide, ozone, nitrogen dioxide, and sulphur dioxide all of which poses a risk to human health.

Air pollution, which is the contamination of the indoor or outdoor environment by harmful substances, has major sour...