Pollution soared to hazardous levels in Delhi on the night of Diwali, the Hindu festival of lights, reaching 40 times the limit recommended by the World Health Organization.

Air quality in Delhi plunged to “severe” levels on the night of Diwali, with the amount of particulate matter (PM) spiking close to 20 times in certain areas, according to data recorded by monitoring stations across the city. Though the Delhi government claimed the 24-hour average ambient level of pollutants, particularly those associated with vehicles, such as nitrogen dioxide, was low compared to last Diwali, real-time data showed high pollution levels.

At 11pm, PM10 was recorded at 2,308 microgram per cubic meter (mpcm) while the prescribed standard is 100mpcm. PM2.5, for which the prescribed standard is 60mpcm, also touched an alarming high at 619mpcm at midnight in this heavily polluted area in East Delhi.

At RK Puram, PM10 was at its peak at 1am at 1,333mpcm while PM2.5 touched 985mpcm at 9.20pm. In Punjabi Bagh, the PM2.5 was at its peak at 1am and was recorded at 638mpcm, while PM10 was recorded as 1,033mpcm highest also at 1am. However, according to the DPCC air quality index, a downward trend was witnessed since 2am across the monitoring stations.

The Delhi government maintained that 24-hour average values of sulphur dioxide, nitrogen dioxide and PM 2.5 were lower this Diwali compared to last year, and claimed it was due to a sustained campaign.