India pollution monitors overwhelmed by toxic smog

India's air pollution monitors faced an overwhelming challenge this week due to a toxic smog so severe that it exceeded their measurement limits, with concentrations being 66 times the World Health Organization's recommended daily maximum, according to regulators. Opposition politicians accused authorities of deliberately allowing gaps in official readings during the Diwali festival, which saw a surge in pollution from fireworks.

New Delhi, one of the world's most polluted capitals, already suffers from winter smog caused by vehicle emissions, farm fires, and industry. However, the missing data meant the official record failed to capture the full extent of the pollution at its worst. The government shut down air quality monitoring stations on Diwali night, leading opposition politicians to question the government's transparency.

The Central Pollution Control Board (CPCB) denied allegations of data fraud, stating that the gaps were due to differences in pollutant concentration measurement rather than attempts to conceal pollution. Extreme episodes like Diwali firecracker bursts can cause gaps in data, but the CPCB clarified that readings beyond the calibrated range are not used in computations.

When the monitors resumed reporting about eight hours after the fireworks, the pollution levels reached 879 micrograms per cubic metre in Mandir Marg locality, which is over 58 times the WHO daily limits.