
Delhi registered two air quality index (AQI) readings on Saturday (November 7) morning: 363 on India’s official scale at 10am and 581 on the US scale used by Swiss group IQAir at 10.35am (0505 GMT).
IQAir’s figure put the capital first in its live pollution ranking of major cities worldwide.
The Central Pollution Control Board classified the official reading as “very poor”.
That figure cannot be compared directly with IQAir’s because the scales and calculation methods differ.
IQAir bases its index on air pollutant concentrations; on that measure, Delhi’s reading was roughly twice the 285 recorded for Lahore in neighbouring Pakistan.
With severe pollution forecast ahead of Diwali, India has instructed schools across Delhi and surrounding areas to make classes available online.
People have also been encouraged to work from home.
Official figures cited by local media showed that Friday marked an eight-year low for Delhi’s pre-Diwali air quality.
The onset of winter brings an annual pollution problem to many parts of northern India.
Cold, dense air holds in emissions from vehicles, dust generated by construction and smoke from burning crop waste.
Diwali, the Hindu festival of lights, falls on Sunday.
Firecrackers are usually set off widely as part of the celebrations, adding to the air pollution.
Source: Reuters