On a particularly smoggy day, when the Air Quality Index (AQI) in a city reaches a value over 300, public health officials consider it an emergency. The AQI is designed to end at 500. This morning, in the New Delhi neighborhood of Punjabi Bagh, the index reached at 999 (or potentially even higher, as some sensors or the reporting website simply may not be set up to deal with AQI levels over 1,000).

The smog has grounded flights, forced the closure of schools through Sunday, and caused a 24 car pile-up on a local highway. It’s not the first time that the air has been this bad in Delhi, which the World Health Organization has previously ranked the most polluted city in the world. Other Indian cities are often equally polluted, leading to serious health problems: Recent data links air pollution in India to the deaths of 1.6 million people in 2016.

Read the source article at fastcompany.com