Indian National Ambient Air Quality Standards stipulate the maximum permissible limit of the annual mean concentration of PM2.5 to be

India's National Ambient Air Quality Standards fix the annual mean limit for PM2.5 at 40 micrograms per cubic metre.

The 60 microgram figure is the annual limit for the coarser PM10, not PM2.5.

The 45 microgram value matches no annual particulate standard in these norms.

The 25 microgram value aligns with WHO guidance rather than the Indian standard.

The 24-hour PM2.5 limit is set higher, at 60 micrograms per cubic metre.

These standards are notified and monitored by the Central Pollution Control Board.