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The city of Delhi experienced an unprecedented weather event in December, marking the highest rainfall in fifteen years and plummeting temperatures to record lows. This extreme weather phenomenon resulted in a significant improvement in air quality, offering a much-needed respite from the persistently hazardous pollution levels that had plagued the region. The heavy rainfall, commencing late Thursday night and continuing intermittently throughout Friday, drastically altered Delhi's atmospheric conditions, leading to a substantial drop in temperature and a remarkable cleansing of the air. The impact on the city's air quality was immediate and dramatic. Days prior to the rainfall, Delhi's Air Quality Index (AQI) had languished in the 'very poor' range, exceeding 300 in several areas. This level of pollution poses significant health risks to residents, necessitating stringent measures to mitigate its effects. The implementation of GRAP-3 restrictions, which included a ban on BS-IV vehicles and a halt to non-essential construction projects, reflected the gravity of the situation.
The arrival of the record rainfall, however, triggered a dramatic shift in the air quality landscape. By Friday morning, the AQI had plummeted to 'moderate' levels, indicating a significant improvement in the overall air quality. This considerable decrease in pollution levels prompted the authorities to lift the GRAP-3 restrictions, easing the burden on commuters and construction industries. The data provided by the Central Pollution Control Board (CPCB) revealed a remarkable reduction in pollution across various locations in Delhi. While some areas, such as Anand Vihar, still recorded AQI levels within the 'moderate' range (220), many others showed readings well within the 'satisfactory' or even 'good' categories. This stark contrast between pre- and post-rainfall AQI levels underscores the significant impact of the heavy downpour on cleansing the Delhi atmosphere.
The unusual rainfall also had a profound effect on the city's temperature. Friday's low of 14.6°C was the coldest December day recorded in Delhi in the past five years, significantly lower than the temperatures recorded on the coldest days of December in the previous four years (2023: 15.9°C, 2022: 15.6°C, 2021: 17.8°C, and 2020: 15.2°C). This dramatic temperature drop, coupled with the persistent rainfall, disrupted the usual temperature patterns, leading to unseasonably low daytime highs. This unexpected cold snap further highlighted the magnitude of the weather event and its wide-ranging impact on the city. The India Meteorological Department (IMD) forecast continues to predict cloudy skies with scattered showers into Saturday, suggesting the weather pattern is not yet fully resolved. The forecast also predicts a further drop in temperature and the onset of dense fog from December 29 onwards, raising concerns about potential visibility issues and further cold spells.
The fluctuating weather conditions underscore the need for robust climate monitoring and preparedness in Delhi. The rapid changes in temperature and air quality highlight the city's vulnerability to extreme weather events. Furthermore, the interplay between rainfall and air quality provides valuable insights into the potential effectiveness of natural cleansing mechanisms in combating air pollution. The contrast between the severe air pollution experienced prior to the rainfall and the significant improvement following the downpour presents a compelling argument for exploring nature-based solutions to urban pollution challenges. The substantial improvement in air quality following the rain also emphasizes the urgent need for long-term strategies to address the root causes of Delhi's persistent air pollution problem. While the recent rainfall brought temporary relief, sustained efforts to reduce emissions from various sources, including vehicles and industrial activities, are crucial to maintaining improved air quality in the long term.
The experience of Delhi highlights the complex relationship between weather patterns, air quality, and public health. The dramatic improvement in air quality following the record rainfall underscores the need for holistic approaches to urban environmental management. This includes not only short-term interventions like GRAP restrictions but also long-term solutions focusing on emission reduction, sustainable urban planning, and public awareness campaigns. By understanding the interplay between these factors, Delhi can strive towards a future where improved air quality and environmental sustainability are prioritized and consistently achieved, reducing the significant health risks associated with severe air pollution. The lessons learned from this recent weather event offer a valuable opportunity to enhance the resilience of the city and to improve the well-being of its inhabitants.
Source: Delhi weather: Record rain and 14.6°C cold mark Capital's frostiest December yet