By N.S. Venkataraman* India’s capital, Delhi, has been suffering from poor air quality during certain periods every year. On 15 December 2025, the Air Quality Index (AQI) was recorded as high as 452. An AQI above 400 falls in the “severe” to “hazardous” category, indicating toxic air that can cause immediate irritation such as burning eyes, coughing and breathlessness, while also increasing the risk of respiratory infections and other health problems.