Air pollution soared in Delhi on Thursday prompting the Supreme Court-mandated EPCA to write to the states in the region to gear up for another round of action under the 'emergency' category.
In his letter, Bhure Lal, chairman of the Environment Pollution (Prevention and Control) Authority, has also directed the states to intensify ground-level action to tackle the pollutant-laden haze which has shrouded the region.
At around 1 pm on Thursday, the concentration of PM2.5 was 320.9 microgram per cubic metre (ug/m3), while PM10 was 496 ug/m3, four units short of the emergency limit of 500 ug/m3.
Under the Centre-notified Graded Response Action Plan (GRAP), pollution is considered severe plus or emergency when readings of ultrafine particulates PM2.5 or PM10 are above 300 and 500 ug/m3 respectively.
Measures listed under the emergency category are rolled out when these conditions prevail for 48 hours at a stretch.
If the EPCA notifies the emergency action plan, which was done during the November smog episode, measures including a ban on entry of trucks, construction activities and the odd- even scheme may have to be enforced in the city.
In the first round, these measures were imposed on November 8 and withdrawn on November 16 after the smog lifted.
The latest spell of pollution started on the night of December 19. Since then, the pollution graph has steadily risen, mainly due to a drastic fall in wind speed which is preventing dispersion of pollutants.