Thick smog shrouds New Delhi after Diwali firecrackers add to seasonal pollution

India's air pollution monitors were overwhelmed by toxic smog so severe that concentrations exceeded their upper measurement limit, which is equivalent to 66 times the World Health Organization's recommended daily maximum, according to regulators cited by Yahoo. The admission followed accusations by opposition politicians that authorities deliberately allowed gaps in official readings for several hours overnight from Sunday into Monday as pollution surged with a barrage of fireworks during Diwali, the Hindu festival of lights. New Delhi is considered one of the world's most polluted capitals, where winter smog from vehicle emissions, farm fires, and industry already chokes millions of residents. The missing readings resulted in official data failing to capture the full extent of the pollution during its worst period.

Opposition figures strongly criticized the administration over the missing metrics. Aam Aadmi Party Delhi president Saurabh Bharadwaj questioned the trustworthiness of the government in a video posted on X, asking how people could trust a government that shuts down monitoring stations on Diwali night and commits data fraud. Senior Congress party lawmaker Ajay Maken also used social media to ask who would answer for the air if Diwali night particulate matter readings were not recorded. Another Congress lawmaker, Pawan Khera, stated that the missing data did not mean the pollution had disappeared, adding that the poisonous smoke would continue to choke lungs, threaten lives, and shorten life expectancy.

The Central Pollution Control Board rejected accusations of deliberate under-reporting, stating that the gaps reflected differences in measurement of pollutant concentration rather than an attempt to conceal pollution. Particulate matter analysers installed under the 2015 National Air Quality Index were calibrated to measure concentrations up to 1,000 micrograms per cubic metre, whereas the World Health Organization recommends a daily maximum of 15 micrograms per cubic metre for PM2.5, which are fine particles capable of penetrating deep into lungs and linking to cancer. The Central Pollution Control Board stated that the automated data validation system treats hourly readings beyond the calibrated range as outside range and excludes them from computations, noting that extreme episodes like Diwali firecracker bursting may appear as data gaps at specific stations.

Although choking clouds filled the streets early Monday, the actual scale of pollution was only captured when monitors resumed reporting roughly eight hours after the fireworks peaked. Readings subsequently reached 879 micrograms per cubic metre in the Mandir Marg locality based on data from a city government station cited by monitoring organisation IQAir, representing more than 58 times the daily limits recommended by the World Health Organization.