Delhi's air quality has slipped back to poor category due to a change in the direction of the wind, which is now flowing from stubble burning areas in Punjab and Haryana, authorities said Monday.
The air quality Sunday had improved to moderate level with an index of 181 but Monday the air quality slipped to the poor category with the Air Quality Index (AQI) at 235, according to data at the Centre-run System of Air Quality and Weather Forecasting and Research (SAFAR).
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.
An official at the Central Pollution Control Board attributed the reason behind the slight improvement on Sunday to less traffic and improvement in wind speed but as the traffic increased on Monday the pollution in the city again rose and the air quality worsened.
The PM10 level (presence of particles with a diametre less than 10mm) was at 230 in Delhi and the PM2.5 level (presence of particles with a diametre less than 2.5 mm) in the city was 101, according to a data by SAFAR.
SAFAR has also forecast further deterioration of air quality in the next two days with the PM10 expected to touch 264 and PM2.5 to reach 111 in the next three days.