Dhaka, Sept. 22 -- The World Health Organisation (WHO) on Wednesday issued its first air quality guidelines since 2005 aimed at reducing deaths from key pollutants that cause cardiovascular and respiratory diseases.

The United Nations agency, in advice to its 194 member states, slashed the recommended maximum levels for several pollutants, including particulate matter and nitrogen dioxide, both of which are found in fossil fuel emissions.

"Air pollution is one of the biggest environmental threats to human health, alongside climate change," it said.

The WHO cited "clear evidence" of the damage inflicted by air pollution on human health "at even lower concentrations than previously understood".

"WHO has adjusted almost all the air quali...