PM1 silently lurks in Lutyens' seemingly crisp air: Study

It would perhaps be wise to junk the perception that Delhi's Lutyens zone with its wide tree- lined boulevards is less polluted than the city's peripheral areas which are visibly dusty.
A study has found a substantial presence of PM1 ultrafine particulates in the Lodhi Road area. These particulates are finer and potentially more harmful than the PM2.5 and PM10 particles which have a larger presence in the capital's air in terms of volume.
The monitoring station of the System of Air Quality and Weather Forecasting And Research (SAFAR) has recorded that the average volume of PM1 during summer, winter and the monsoon remain around 46, 49 and 20 micrograms per cubic metre respectively.

However, it has not attracted much attention till now as the safe standards of PM1 have not been defined yet, in the absence of which its potentially harmful effects have not been documented, scientist Gufran Beig, the project director of SAFAR, told PTI.
Presently, only SAFAR, which comes under the Ministry of Earth Sciences, monitors PM1 in the national capital.
"Globally you may not have a standard but PM1 is considered the most dangerous among all particulate matter, particularly because of its size. It measures around 1 micron or less in diameter.