Delhi recorded its first ‘poor’ air quality day of the season on Wednesday, with the Air Quality Index (AQI) climbing to 245, its highest level in the past 100 days, as temperatures began to dip. The worsening air quality prompted authorities to enforce the first stage of the Graded Response Action Plan (GRAP) across Delhi-NCR to curb pollution levels.
The last time Delhi recorded a similar AQI was on July 13, when the index stood at 246, according to available data. The Commission for Air Quality Management (CAQM) announced the implementation of Stage I of GRAP on Wednesday after the capital’s air quality moved into the ‘poor’ category, triggering the first set of preventive measures under the pollution-control framework.
According to the forecast issued by the Air Quality Early Warning System, pollution levels in Delhi are expected to remain in the ‘poor’ category until October 23. The outlook for the following six days also points towards continued poor air quality, suggesting that residents may have to contend with elevated pollution levels over the coming week.
Weather conditions are expected to play a significant role in how pollution builds up over the city. The Early Warning System has identified a ventilation index below 6,000 square metres per second, coupled with an average wind speed of less than 10 kilometres per hour, as unfavourable conditions for the dispersal of pollutants. When winds remain weak and atmospheric ventilation is limited, pollutants tend to accumulate closer to the ground, contributing to a deterioration in air quality.
The decline in air quality was recorded a day after Vijayadashami, when Ravan effigies were set alight at several locations across the capital as part of the festival celebrations. However, authorities have not established a direct connection between the festivities and the subsequent rise in pollution levels. The deterioration comes as Delhi enters a period when changing weather conditions can make the dispersal of pollutants increasingly difficult.
Data from the Decision Support System for Air Quality Management in Delhi, developed by IITM Pune, showed that the transport sector within the city was the biggest contributor to pollution on Tuesday, accounting for 20.5 per cent of the total. The figures underline the significant role played by vehicular emissions in the capital’s pollution burden, alongside emissions from several other sources within Delhi and the surrounding National Capital Region (NCR).
Stubble burning accounted for as much as 8 per cent of the pollution contribution recorded by the system. Residential sources made up 5.2 per cent, while peripheral industries contributed 4.3 per cent. Construction activities accounted for 2.8 per cent, followed by waste burning at 1.8 per cent, road dust at 1.4 per cent and other sources at 1.3 per cent.
The assessment also identified contributions from several districts across the NCR, highlighting the regional nature of Delhi’s air pollution. Jhajjar was the largest contributor among the listed districts, accounting for 8 per cent, followed by Gurugram at 5.7 per cent and Sonipat at 4.8 per cent. Ghaziabad contributed 3.04 per cent, while Panipat accounted for 2.9 per cent and Gautam Buddh Nagar contributed 2.6 per cent.
Other districts also added to the overall pollution load. Baghpat accounted for 2.27 per cent, followed by Faridabad at 1.7 per cent and Rohtak at 1.5 per cent. Karnal contributed 1.2 per cent, while Rewari accounted for 1.19 per cent. Bhiwani and Alwar contributed 0.8 per cent and 0.7 per cent, respectively, while Mahendragarh accounted for 0.5 per cent. Contributions grouped under other sources stood at 13.28 per cent.
The AQI reading of 245 places Delhi in the ‘poor’ category under the classification system used by the Central Pollution Control Board (CPCB). The board categorises AQI values between 0 and 50 as ‘good’, readings from 51 to 100 as ‘satisfactory’ and levels between 101 and 200 as ‘moderate’. An AQI of 201–300 falls in the ‘poor’ category, while readings between 301 and 400 are classified as ‘very poor’. Values ranging from 401 to 500 are considered ‘severe’.
With forecasts indicating that poor air quality could persist in the days ahead, the coming week will be important in determining whether pollution levels stabilise or deteriorate further. The combination of unfavourable weather conditions and emissions from transport, residential activity, industry and sources across the NCR remains a concern as Delhi moves deeper into the seasonal period associated with worsening air quality.
This article was prepared with AI assistance and is based on information available in the public domain.
