Delhi's Diwali Miracle: Strong Winds Make 2024 Post-Diwali Air Second Cleanest Since 2015!
Delhi experienced an unexpected improvement in air quality following Diwali in 2024, with post-Diwali AQI levels being the second cleanest since 2015. While stubble burning and increased local emissions contributed heavily to the pollution, strong winds and warmer temperatures created an unusual ventilation effect, dispersing pollutants and providing a temporary reprieve from severe air quality conditions. Experts noted that while the short-term improvement is promising, the long-term pollution trends highlight ongoing challenges in managing Delhi's air quality, especially as winter inversion effects set in.
Arpit Shakya 
INDC Network : New Delhi : For Delhi’s residents, Diwali often brings mixed feelings. While the city celebrates with lights and festivities, the celebrations often culminate in deteriorated air quality due to excessive firecracker use, stubble burning, and seasonal weather patterns. However, in a surprising turn of events, Diwali 2024’s post-celebration air quality marked the second cleanest since 2015. Strong winds helped disperse the dense smoke from firecrackers and pollutants in Delhi’s skies, improving the Air Quality Index (AQI) from “severe” to the “very poor” category – a reprieve that was unexpected given previous years' patterns.
On Thursday night, as Diwali celebrations reached their peak, AQI levels spiked sharply due to the combined effects of local emissions, toxic gases from firecracker use, and stubble burning from neighboring regions. The AQI readings rose significantly through the night, climbing from 328 in the early evening to a concerning 362 by early Friday morning. While it seemed inevitable that Friday would bring another day of “severe” air quality, Delhi’s residents witnessed an unexpected turn in the late morning as winds picked up speed and temperatures remained relatively warm, improving ventilation across the city. The AQI subsequently dropped to 339 by 4 p.m. and further to 323 by the evening, sparking optimism amidst air quality concerns.
Meteorological experts have attributed this improvement to the favorable wind conditions observed on Diwali and the following day. According to Mahesh Palawat, vice president at Skymet meteorology, higher temperatures helped maintain a mixing height as high as 2,100 meters. Mixing height represents the vertical distance pollutants can move upwards from the surface. In typical winter months, this mixing height can fall to as low as 200-300 meters, leading to the trapping of pollutants near the surface, thereby worsening air quality. This phenomenon, known as “inversion,” was notably absent on Friday, allowing pollutants to be swept away more freely.
The wind speeds, which varied between 12 and 16 kilometers per hour through Diwali night and dropped briefly but picked up again by morning, were key to diluting Delhi’s pollution. Palawat explained that these sustained wind speeds played a crucial role, allowing pollutants to disperse instead of concentrating near the surface. Additionally, the absence of deep inversion conditions – typical of colder winter months – offered further relief. Without inversion, pollutants remained better dispersed, providing a temporary yet much-needed reprieve from severe pollution levels.
Anumita Roychowdhury, Executive Director of Research and Advocacy at the Centre for Science and Environment (CSE), added that although Delhi experienced a drop in pollution on Friday, October had already recorded more days with “poor” and “very poor” air quality than previous years. She also highlighted that local emissions played a substantial role in AQI deterioration, given that the contribution from stubble burning was still relatively low for most of October, only peaking at around 27.61% on Diwali day itself. This spike, though significant, contrasts with previous years when farm fires were a more dominant contributor.
Despite the day-after-Diwali improvement, hourly spikes in PM2.5 concentrations across various parts of the city exceeded the national permissible limits by more than 30 times. This disparity underscores the pressing need to address regional pollution sources and local emissions collectively. As the colder months approach, Delhi’s pollution levels are expected to rise due to increasing inversion effects, which could trap pollutants closer to the ground. This natural phenomenon is anticipated to exacerbate the air quality situation, underscoring the importance of sustainable, long-term air quality management solutions.
The Diwali period in 2024, while a short-term success story, has highlighted the complex interplay between meteorological factors, local emissions, and seasonal agricultural practices that influence Delhi’s air quality. The strong winds and warm conditions have provided temporary relief, but experts caution that ongoing improvements will require dedicated efforts to reduce emissions from firecrackers, industrial activities, and vehicular pollution, alongside stricter regulations on stubble burning.
While Delhi celebrates this unexpected improvement, it is also a reminder of the city’s fragile air quality and the broader challenges in maintaining these gains. Continuous monitoring, adaptive policies, and collective efforts from the public and private sectors remain crucial to transforming this temporary relief into a sustainable future.
