Delhi's brief tryst with cleaner air came to an abrupt end on Sunday as the national capital's air quality index (AQI) plunged back into the 'Very Poor' category, recording a value of 307. This marked a significant deterioration after the city experienced a short-lived improvement over the previous two days.
A Sudden Reversal After Brief Relief
The capital had witnessed a marginal improvement in air quality on Friday and Saturday, with AQI readings of 236 and 276 respectively, both falling in the 'Poor' category. However, this relief was short-lived. By Sunday, a combination of meteorological factors led to the accumulation of pollutants, pushing the AQI past the 300 mark into the 'Very Poor' zone.
The decline was not limited to Delhi alone. The broader National Capital Region (NCR) mirrored this troubling trend. Neighbouring Noida recorded an AQI of 307, while Gurgaon's air quality was even worse at 333, both categorised as 'Very Poor'. This was a sharp fall from their Saturday levels of 242 and 244 respectively.
Why Did the Air Quality Worsen Again?
The India Meteorological Department (IMD) had predicted this deterioration in its weekend forecast. The primary culprit was identified as reduced wind speed. While increased wind velocity in the preceding days had helped disperse pollutants, the calmer conditions on Sunday allowed harmful particulate matter to concentrate near the surface.
Data from the Indian Institute of Tropical Meteorology (IITM) Pune's Decision Support System (DSS) shed light on the major sources of Delhi's PM2.5 pollution on Sunday. Transport emissions emerged as the top contributor, accounting for 13.6% of the PM2.5 load. This was closely followed by emissions from the industrial sector at 11.4%.
Other local sources included residential emissions (3.3%), while waste burning, construction activity, and road dust together contributed approximately 5%. The data also highlighted the significant role of external sources from neighbouring regions. Jhajjar was the highest external contributor at 17.5%, followed by Sonipat at 7.7%.
Weather Outlook and Temperature Trends
According to the IMD, the maximum and minimum temperatures in Delhi were recorded in the ranges of 16°C to 18°C and 7°C to 9°C respectively. The weather office has forecast a partly cloudy sky for the next 24 hours, followed by mainly clear conditions for the subsequent four days. The forecast also predicts shallow fog during the night of January 4th, with shallow to moderate fog likely to prevail over most parts of the city during morning hours in the coming days.
The rapid return of 'Very Poor' air quality underscores the persistent and complex nature of Delhi's winter pollution crisis, where even temporary improvements remain vulnerable to changes in weather patterns and continuous emissions from multiple local and regional sources.
