Another Diwali same toxic tale Delhi chokes as curbs go up in smoke

     New Delhi, Nov 9 (PTI) A story repeated every year, with little changing -- a toxic haze engulfs Delhi on Diwali night as pollution levels soar, firecracker restrictions are brazenly flouted and questions are raised over the reliability of the AQI tracking exercise itself.

     The national capital on November 8 recorded its most polluted Diwali in five years, exposing glaring enforcement failures and raising serious concerns over the health risks faced by Delhiites.

     The average AQI (Air Quality Index) was recorded at 376 on Sunday at 4 pm -- the highest for a Diwali day since 2021.

     The instantaneous AQI stood at 371 at 10 pm on Sunday, after the deadline for bursting crackers had passed, as a thick layer of smog enveloped the city.

     Delhi recorded an average PM2.5 concentration of 257 micrograms per cubic metre on Diwali --- more than four times the national 24-hour standard of 60 micrograms per cubic metre and over 17 times the World Health Organisation's 24-hour guideline of 15 micrograms per cubic metre.

     Despite the restrictions, firecrackers continued to be burst well beyond the permitted hours (8 pm to 10 pm), with enforcement agencies failing to effectively curb the violations in many parts of the city.

     Several monitoring stations went offline on Sunday night during the peak period of firecracker use in the national capital, raising questions over the reliability of the AQI tracking exercise itself.

     An analysis of hourly PM2.5 data from the city's 59 monitoring stations showed that while only one station was not reporting readings at 7 pm on Sunday, the number rose to 36 by 1 am on Monday, leaving readings available from just 23 stations.

     The situation improved gradually, and by at 8 am, only seven stations were missing data.

     The Sameer app also showed gaps in the network on Monday: 51 stations were reporting at 8 am, 49 at 10 am and 2 pm, and only 47 by 4 pm.

     The missing readings prompted concerns over the reliability of the monitoring network.

     Anumita Roychowdhury, executive director of the Centre for Science and Environment, said the failure to provide real-time readings during peak Diwali pollution was difficult to explain.

     "When substantial public funds have been invested in establishing Delhi-NCR's air quality monitoring network - the densest in the country - backed by active operation and maintenance contracts, a data eclipse precisely during peak Diwali pollution is inexplicable," she said.

     "While the severity of exposure is evident on the ground, credible official data is needed for institutional accountability, public awareness and mitigation. Losing data does not reduce the public health emergency," she added.

     The AQI readings put out by private agencies, however, painted a much more unpleasant picture than what the official figures reflected, with most parts of Delhi-NCR reporting extremely hazardous air pollution levels, leading experts to cast doubts over government data.

     Private agency AQI.in reported an AQI of 637 on Monday morning, placing the air in the "hazardous" category. The figures reported by private platforms are not directly comparable with CPCB readings, as agencies may use different scales, averaging periods and measurement methods.

    Further, readings for PM2.5, the fine inhalable particles which could trigger chronic concerns over long-time exposure, at individual monitoring stations were quite high.

     Siri Fort recorded a maximum PM2.5 concentration of 1,000 micrograms per cubic metre till noon on Monday, the highest value displayed on the Central Pollution Control Board's public portal.

     It was followed by Punjabi Bagh at 993, IGI Airport Terminal 3 and Chhawla at 989 each, IMD Lodhi Road at 987, Shadipur at 967, ITO at 966, CRRI Mathura Road at 965, Aya Nagar at 961 and Lodhi Road at 958.

     The Central Pollution Control Board (CPCB) portal does not display readings above 1,000 micrograms per cubic metre.

     Experts said this raised questions about how extreme pollution levels were being represented in publicly available data, as concentrations beyond that limit could not be quantified through the portal.

     Centre for Research on Energy and Clean Air (CREA) ranked this year's Diwali as the fourth most polluted since 2016 and the fourth most polluted day of 2026. The three preceding days -- November 5, 6 and 7 -- were also among the eight most polluted days recorded in the city this year.

     Weather conditions also played a role in the changing pollution levels. Experts said reduced wind speeds affected the dispersion of pollutants, while easterly winds influenced the movement of pollution over the city.

     Dr Vikas Mittal, director and pulmonologist at CK Birla Hospital, Delhi, said elevated PM2.5 and PM10 levels could trigger airway inflammation and worsen conditions such as asthma and chronic obstructive pulmonary disease.

     The missing readings also triggered a political confrontation.

     Aam Aadmi Party leader Saurabh Bharadwaj accused the Delhi government of manipulating air quality data to understate pollution levels.

     He alleged that 20 new monitoring stations had been installed in open and green areas with relatively less traffic and population to bring down the city's average readings. He also claimed that water was sprinkled near a monitoring station in Jahangirpuri to lower pollution readings.

     "Similarly, the government switched off AQI monitoring stations on Diwali night and committed data fraud. How do you trust such a government?" he said.

     Delhi Cabinet minister Kapil Mishra, when asked about monitoring stations that were not reporting data, asked reporters to share details and said he would seek action. He also raised allegations of a conspiracy surrounding stubble burning.

     Radhey Shyam Sharma, head of the Department of Environmental Studies at Delhi University, said transparency and accountability were important during a severe pollution episode.

     Differences in measurement methods and averaging periods could lead to variations in readings reported by different agencies, he said, adding that missing data could leave residents uncertain about the actual situation. PTI SGV AHD SHB BM BUN AMJ

AMJ

(This story has not been edited by THE WEEK and is auto-generated from PTI)