Residents of India's capital finally experienced a breath of fresher air this Saturday, as Delhi's notorious air quality showed a significant, though likely temporary, improvement. For the first time in many days, the city's average Air Quality Index (AQI) dropped into the 'poor' category, providing a much-needed respite from the severe pollution that has been plaguing the city.
Marked Improvement in Pollution Levels
The data tells a clear story of improvement. By 5 PM on Saturday, the city's average AQI had fallen to 300, officially entering the 'poor' zone. This was a notable decline from the 4 PM reading of 305, which itself was a significant drop from Friday's 369 and Thursday's 377. The cleanest air of the evening was recorded at 9 PM, with an AQI of 287, marking the best air quality Delhiites have breathed in weeks.
For the first time in days, no area in the city recorded air quality in the 'severe' category. However, pollution levels remained high in several pockets including Narela, Shadipur, Jahangirpuri, Nehru Nagar, Vivek Vihar, Bawana, Okhla, Anand Vihar, and Rohini.
What Caused the Cleaner Air?
The primary reason for this welcome change was a shift in weather patterns. After days of stagnant conditions that trapped pollutants and created a dense smog layer, surface wind speeds picked up to around 15 kilometers per hour through the afternoon. These better wind speeds and improved ventilation helped disperse and flush out the accumulated pollutants.
An analysis by the Decision Support System revealed that transport contributed the single largest share to PM2.5 levels at 18%, followed by industrial and residential emissions. Interestingly, the share of pollution from stubble burning remained minimal, at just 0.9% on Friday and an estimated 1.2% on Saturday, making local emissions the dominant source of the city's pollution load. Neighbouring Haryana's Sonipat and Panipat also contributed to Delhi's pollution.
A Temporary Respite with Poor Air Forecast
Unfortunately, this period of cleaner air is not expected to last. According to the Indian Institute of Tropical Meteorology's Air Quality Early Warning System, the air quality is likely to deteriorate back to the 'very poor' category from November 30 for a few days.
The forecast indicates that northwesterly surface winds will prevail through Sunday, strengthening to 10-15 kmph in the morning and afternoon before slowing down again by the evening. A critical measure, the ventilation index, which gauges the atmosphere's ability to disperse pollutants, is projected to drop from a favourable 6800m²/s on Sunday to an unfavourable 4500m²/s on Monday, before seeing a slight improvement on Tuesday.
On the temperature front, Delhi recorded a minimum of 10.4 degrees Celsius on Saturday, up from 8.1 degrees the previous day, and a maximum of 26.5 degrees Celsius. For Sunday, the city can expect a maximum temperature of 23-25 degrees Celsius and a minimum of 8-10 degrees, with the possibility of shallow morning fog.
