Air quality has been deteriorating across India amid winter. Over the last three months, the Air Quality Index (AQI) has fallen dangerously low in the northern regions of the country, especially in New Delhi, where it is on the brink of "emergency" level.
Faced with rising air pollution in Delhi-National Capital Region (NCR), the Centre had introduced a new law through an ordinance that puts in place a powerful oversight body and provides for up to five years of jail term and Rs 1 crore fine for violators with immediate effect.
While the AQI hovering in the "hazardous" levels (especially in the late stages of winter) has been a concern for many years, medical experts have warned that air pollution can aggravate the ongoing COVID-19 pandemic.
Here's the AQI of major Indian cities as of 7.10 am on December 31:
| City | AQI | PM2.5 |
| New Delhi | 347 | 193 |
| Mumbai, Maharashtra | 224 | 95 |
| Kolkata, West Bengal | 322 | 150 |
| Chennai, Tamil Nadu | 63 | 36 |
| Hyderabad, Telangana | 203 | 91 |
| Bengaluru, Karnataka | 108 | 32 |
| Ahmedabad, Gujarat | 122 | 62 |
PM2.5 is the mixture of solid particulate matter and liquid droplets found in the air. Breathing such air can affect the heart and cause chronic cardiovascular problems.
AQI between 0 and 50 is considered "good", 51–100 is "satisfactory", 101–200 is "moderately polluted", 201–300 is "poor", 301–400 is "very poor" and 401–500 is considered "severe". The categorisation may vary depending on the monitoring agency.
