Delhi’s air quality fell into the severe category on November 9, with the CPCB recording an overall AQI of 483 and at least 15 stations above 400, according to reports.
Stage III of the Graded Response Action Plan, in force since November 6, halts non-essential construction and demolition, adds vehicle restrictions and moves classes up to primary school level to hybrid, which affects builders, logistics firms and schools directly.
For businesses, the uncertainty in the data is also a cost. Reports gave Delhi’s figure as 370, 483, 776 and above 1,000 depending on the source and method, which makes it hard to know which readings regulators will act on.
Readers should check live CPCB and CAQM data.
The Hans India and Daily Jagran city tables, citing CPCB data for November 9, give Delhi a figure of 370, in the very poor category, which differs from the 483 overall figure.
The Hans India also reports a reading of 776 for Delhi from AQI.in at 6:51 am on Monday, which comes from a private platform and not from the CPCB.
Organiser reports that Swiss-based IQAir recorded readings above 1,000 in Shahdara and Defence Colony, without giving times or exact values, and says the difference reflects variations in methodologies.
The Air Quality Index runs from 0 to 500, with 0 to 50 good, 51 to 100 satisfactory, 101 to 200 moderate, 201 to 300 poor, 301 to 400 very poor and 401 to 500 severe, according to Organiser.
Readings above 500 are shown as 500 or 500 plus on the official scale, which is one reason private platforms can show higher numbers.
The Graded Response Action Plan Stage III was put in place across Delhi-NCR on November 6, according to Organiser, three days before the Diwali period it describes.
Stage III measures include a halt to non-essential construction and demolition, extra vehicle restrictions and hybrid classes up to primary school level, according to Organiser.
Smog over the Indus-Ganga Plain, NOAA satellite image of 2017 (file image), Wikimedia Commons, public domain