Delhi’s PM2.5 pollution rose to more than 30 times the World Health Organization’s daily guideline in parts of New Delhi on Wednesday, November 4, as dense smog covered the capital before Diwali.
Air-quality monitor IQAir recorded levels above 461 micrograms per cubic metre in some areas. The WHO’s guideline for a 24-hour period is 15 micrograms per cubic metre. Delhi’s citywide Air Quality Index reached 369 early Wednesday.
Twenty of the city’s 59 monitoring stations reported “severe” conditions, while most of the others recorded “very poor” air. Authorities had already tightened pollution-control measures, including restrictions on traffic and construction. But the worsening air showed how difficult it was to contain the seasonal smog.
Vehicle emissions, crop-residue burning and industry all contribute to the pollution. Pollutants also react in the air to form fine particles. Diwali was due to fall on November 8, and officials and residents were concerned about the pollution.
They feared fireworks could add to air pollution that was already dangerous. The WHO says PM2.5 can harm health. Its guideline is intended to help reduce the risks of exposure to air pollution.