Delhi's air quality remained 'poor' for the second consecutive day today. The authorities forecast it to further deteriorate in the next couple of days due to change in direction of wind, which is now flowing from stubble burning areas in Punjab and Haryana.
The overall air quality index (AQI) recorded at 4 pm today was 256 which falls under 'poor' category.
On Monday, the AQI of Delhi was registered at 262, according to the data by the Centre-run System of Air Quality and Weather Forecasting and Research (SAFAR).
Ghaziabad and Gurgaon recorded 'very poor' air quality at 307 and 328 respectively, according to the Central Pollution Control Board (CPCB) data.
The SAFAR has predicted further deterioration of air quality with increase in the dangerous PM2.5 (presence of particles with diameter less than 2.5 micrometers) which is expected to fall under the 'very poor' category in the next couple of days.
The PM2.5 level is expected to reach 124 by Wednesday, the SAFAR data showed.
The PM2.5, also called "fine particulates," is a more serious health concern than PM10, since smaller particles can travel more deeply into lungs and cause more harmful effects.
An AQI between 0-50 is considered 'good', 51-100 'satisfactory', 101-200 'moderate', 201-300 'poor', 301-400 'very poor', and 401-500 'severe'.
The PM10 level in Delhi on Wednesday (presence of particles with diameter less than 10 micrometers) was at 242 and the PM2.5 level 107, the data showed.
The drop in the air quality is due to change in direction of wind, which is now flowing from areas in Haryana and Punjab where stubble burning is taking place, a CPCB official said.
"This is the period of monsoon withdrawals and a low pressure system in the Arabian Sea is developing. Such large scale processes tends to calm the wind speed which is usual for this time," project director at SAFAR, Gufran Beig, said.
"This tends to increase the pollution level. The impact of local transport is insignificant so far," Mr Beig said.