The Delhi government is being urged to declare a city-wide health emergency, as residents endured a third straight day of heavy pollution.

Air quality readings in India’s capital have soared since Tuesday, with one monitor showing levels in the city were 969 — the World Health Organization considers anything above 25 to be unsafe.
Those levels are based on the concentration of fine particulate matter, or PM 2.5, per cubic meter. The microscopic particles, which are smaller than 2.5 micrometers in diameter, are considered particularly harmful because they are small enough to lodge deep into the lungs and pass into other organs, causing serious health risks.

Officials scrambled to provide a response as TV stations looped video of reporters taking live pollution readings amid a background of thick smog. On the street, residents tied scarfs across their faces as makeshift masks…