Delhi’s Diwali AQI Hits Five-Year High as Stations Go Offline

Delhi recorded an average Air Quality Index (AQI) of 376 on Diwali, its highest Diwali reading in five years, as numerous monitoring stations stopped reporting during the overnight pollution peak. Official readings the next morning remained in the very poor range, while private platforms reported substantially different figures.

An analysis by the Centre for Research on Energy and Clean Air (CREA) found that 36 of Delhi’s 59 monitoring stations were not reporting at 1 a.m. Monday, leaving 23 with readings. At 2 a.m., 35 stations lacked data. The number of stations with missing readings had risen through the night from one at 7 p.m. Sunday, according to the analysis.

The official average AQI was reported at 371 at 10 a.m. Monday in one account and 370 at 9:05 a.m. in another. A separate report put the official reading at 370 at 8 a.m. IQAir reported 245 at 8:30 a.m. on the US AQI scale, while AQI.in reported 637 that morning and said the post-Diwali peak reached 2,283. These readings were taken at different times and, in IQAir’s case, used a different scale.

CREA’s account said the data gaps gradually eased during Monday morning, but 47 of the 59 stations were reporting at 4 p.m....