NEW DELHI: Air quality today plunged into the 'severe' category in places across Delhi, with real time readings showing PM 2.5 five times above the prescribed limit at times, which has the potential to affect healthy people and "seriously impact" those with existing respiratory ailments.
The sudden spike in the quantity of pollutants across the capital was attributed by IMD to calm wind movement and an increase in the amount of humidity. Although the 24-hour average remained 'poor', two notches below 'severe'.
"There has been a spurt as the polluting particles, of microscopic sizes, are not getting dispersed due to the atmospheric conditions. The 24-hour average of PM 2.5 and PM 10 were 197 and 330 micrograms per cubic metre respectively," an IMD official explained.
Although visibility averaged above a kilometre, it will start coming down once the temperature drops to single digit which will be followed by formation of fog and subsequently smog, the official said. The real time readings of Delhi Pollution Control Committee (DPCC) stations had PM 2.5 and PM 10 at 381 and 647 micrograms per cubic metre in Anand Vihar while the same were at 339 and 498 in Mandir Marg, the two most polluted spots of the city.
'Severe', declared when PM 2.5 and PM 10 cross 253, 421 micro gram per cubic metres respectively, affects healthy people and seriously impacts those with existing diseases.
On prolonged exposure to 'very poor' quality air, which signifies PM 10 and PM 2.5 levels between 351 and 420, and 211 to 252 micro gram per cubic metre respectively one can develop respiratory illness.
Permissible levels of PM (particulate matter) 2.5 and PM 10 are 60 and 100 micrograms per cubic metre respectively. These particles, which are the major pollutants in the capital's air, can harm the respiratory system as the particles embed themselves deep inside the lungs.
National air quality index of CPCB also had 'severe' readings of the Punjabi Bagh, Mandir Marg and R K Puram stations, where PM 2.5 was the most prominent pollutant.
System of Air Quality and Weather Forecasting And Research (SAFAR) stations in Delhi University, IGI Airport, Dhirpur had air in the 'severe' category as well, bordering 450 in most cases.
These respirable particulate matters, a product of vehicle emissions, burning of waste, industrial plumes, especially PM 2.5 is considered by the World Health Organisation (WHO) as the best indicator of the level of health risks from air pollution.