After getting relief for two days, Delhi's air quality deteriorated again to the ‘severe’ category on Saturday, with AQI crossing 400.

Delhi's worsening air quality is causing respiratory distress in animals, impacting their health and behavior, veterinarians and activists warn.

The respite from extremely toxic air did not last very long for the residents of Delhi. The city’s air quality index (AQI) reading on Saturday returned to the ‘severe’ category after being in the ‘very poor’ zone for two days. In fact, the national capital, which had the day’s worst AQI as per Central Pollution Control Board (CPCB) data, was the only city in the country to report ‘severe’ air pollution. While the average AQI in the Capital on Thursday was 412, the adjoining cities were much less polluted with Noida at 322 (‘very poor’), Ghaziabad at 339 (‘very poor’), and Gurugram at 265 (‘poor’). The ‘severe’ category AQI affects healthy people and seriously impacts those with existing diseases, as per the CPCB. The AQI is a measurement of air pollution on a scale of 0-500. A higher value suggests an increase in toxicity. An AQI reading between 201 and 300 is considered ‘poor’, 301 and 400 ‘very poor’, 401 and 450 ‘severe’, and 451 and 500 ‘severe plus’.