Delhi has failed spectacularly in preventing the air quality from falling into the "dangerous" category on Diwali. The morning after, Anand Vihar was among the areas in Delhi where the air quality index (AQI) was recorded at an alarming 999 this morning. The AQI around Major Dhyan Chand National Stadium touched 999 (the maximum level for the monitors) while the US Embassy in Chanakyapuri scored 459, all under the "hazardous" category.