Hours after pollution norms under GRAP-3 were imposed, Delhi and nearby areas saw the curbs being made stricter on Saturday evening and GRAP-4 being brought in.
GRAP 3 curbs had been imposed by the Commission for Air Quality Management (CAQM), the central body charged with taking steps to tackle pollution in Delhi and neighbouring states, in the afternoon after the Air Quality Index (AQI) crossed the 400 mark and entered the ‘Severe’ category.
In the evening, the CAQM noted that the AQI, which was recorded at 431 at 4 pm, showed an increasing trend and stood at 441 at 6 pm.
Under GRAP, the air quality is categorised into four stages: Poor (AQI 201-300), Very Poor (AQI 301-400), Severe (AQI 401-450) and Severe Plus (AQI above 450).
“Keeping in view the prevailing trend of air quality and in an effort to prevent further deterioration of air quality in the region, the CAQM Sub-Committee on GRAP decides to invoke all actions as envisaged under Stage-IV of the extant GRAP – ‘Severe+’ Air Quality (DELHI AQI > 450), with immediate effect, in the entire NCR. This is in addition to the actions under Stages I, II & III of extant GRAP already in force in NCR,” the CAQM said in a statement.
Explaining the reasons for the worsening AQI, the CAQM said the feeble Western Disturbance approaching north-west India was the main contributing factor, and not local emissions.
“This prevailing meteorological condition has (seen a) marked reduction in wind speed, at times becoming calm, a shift in wind direction from westerly to easterly, and an increase in moisture content in the lower atmosphere. Such conditions during the winter season are conducive to the formation of smog and fog, resulting in poor dispersion and trapping of pollutants near the surface. Owing to these adverse meteorological conditions, a sudden deterioration in air quality has been observed,” it said.