The air in the national capital appears to be most polluted in the morning hours, with particulate matter levels seen at their peak at the time considered most suitable for morning walks or jogging.

On Tuesday, the PM2.5, or the particles in air with diameter less than 2.5 mm, crossed the “very poor” mark and touched “severe”, at several places including Anand Vihar in east Delhi, Punjabi Bagh in west Delhi, Mandir Marg in central Delhi and others during the morning hours.

PM2.5 is one of the major and common pollutant with direct consequences on life expectancy. Any recorded value between 251-350 is considered “severe” for PM2.5, while value between 121 to 250 units is considered “very poor”.

“PM2.5 is the prominent or lead pollutant because when Air Quality Index (AQI) is calculated, we need to see whcih is the prominent pollutant,” Gufran Beig, Project Director, System of Air Quality and Weather Forecasting and Research (SAFAR) said.

According to the real time data recorded by Delhi Pollution Control Committee (DPCC) on Tuesday, between 4 a.m. to 9 a.m., the PM2.5 levels at Anand Vihar ranged between 258 to 225. At about 7 a.m., PM2.5 dropped to 186, considered “very poor” but by 8 a.m., it again increased to 225.

The severe value of PM2.5 affects healthy people and seriously impacts those with existing diseases. The international permissible limit for PM2.5 is 25 micro grammes per cubic metre while for India, it is 60.

Meanwhile at Mandir Marg, PM2.5 reached all time high at 8 a.m. at 340. At Punjabi Bagh, the value was recorded at 270 and at R.K. Puram in south Delhi, PM2.5 between 7 a.m. to 8 a.m. was recorded 209 to 211 units.

The peak value of other major pollutant PM10 – particles in air with diameter less than 10 mm – oscillated between 467 and 696, between 4.30 a.m. to 6.30 a.m. at Anand Vihar.

For PM10, any value between 431 to 550 is considered “severe” with the permissible limit being 100.

At other places like Punjabi Bagh and Mandir Marg, the value was still two to three times higher than the permissible limit.

According to SAFAR, Delhi, on Tuesday, at three areas – Delhi University, Pitampura (both north Delhi) and Mathura Road (south Delhi) – had “very poor” air quality in terms of PM2.5. In other places including IGI Airport, Dhirpur, New Delhi, Ayanagar, and adjoining Gurugram (Haryana) and Noida (Uttar Pradesh), the air quality was placed under “poor” category.

Meanwhile, 15 monitoring stations of Central Pollution Control Board (CPCB) found the PM10 and PM2.5 as the major source of pollutants. On Tuesday, with slight improvement in the index value, the AQI of Delhi was still “poor”.