Haze enveloped Delhi and its suburbs on Tuesday, with the capital recording its air quality index (AQI)in the very poor category for the fourth day on the trot. The city's average AQI was recorded at 359, the highest this season so far. Rohini (410) and Mundka (433) recorded their air quality in the severe zone (AQI above 400). According to Central Pollution Control Board (CPCB) data, the capital recorded an AQI of 210 in October this year was the worst since 2020, compared to 210 in October last year and 173 in October 2021 due to the lack of rainfall.
The AQI recorded 347 on Monday, 325 on Sunday, 304 on Saturday and 261 on Friday, 256 on Thursday, 243 on Wednesday and 220 on Tuesday in Delhi. The AQI was 232 in neighbouring Ghaziabad, 313 in Faridabad, 233 in Gurugram, 313 in Noida and 356 in Greater Noida.
Starting from Wednesday, only electric, CNG and BS VI-compliant diesel buses will be allowed to operate between Delhi and the cities and towns of Haryana, Uttar Pradesh and Rajasthan falling within the national capital region. Delhi metro and buses under the DTC will increase their trips so that passengers can use public transport for their journey requirement.
A data from the Union ministry of earth sciences has showed that vehicular emissions and pollution from the neighbouring regions were the major reasons behind Delhi’s deteriorating air quality on Tuesday. According to a numerical model-based system developed by the Indian Institute of Tropical Meteorology in Pune, vehicular emissions (11 percent to 15 percent) and stubble burning (seven percent to 15 percent) currently stand as the two major contributors to the city's very poor air quality. It also shows that pollution sources in Gautam Buddha Nagar, Uttar Pradesh, are responsible for up to 14 percent of the air pollution in the capital.
The CPCD data shows the daily average AQI for Delhi during the above noted period during the current year has been recorded as 172 against 187 in 2022, 179 in 2021, 156 in 2020, 193 in 2019 and 201 in 2018 respectively, during the corresponding period. Delhi saw just one rainy day (5.4 mm of precipitation) in October 2023, in contrast to six in October 2022 (129 mm) and seven in October 2021 (123 mm).
The Commission of Air Quality Managemnt (CAQM) said the average wind speed during October 2023 was relatively low and spells of absolutely "still" conditions were also observed during the month. According to CPCB data, the capital did not record even a single day with 'good' air quality, whereas there were two such days in 2022 and one in 2021.
The CAQM, however, reported that Delhi registered an AQI of 172 from January 1 to October 31 this year, the second-best for the corresponding period in six years. The city recorded better air quality during this period only during the COVID-19 pandemic-affected 2020. In 2022, 2021, 2019 and 2018, the average AQI during this period ranged from 179 to 201, the CPCB said in a statement. Delhi recorded a single day scant rainfall of only 5.4 mm in the month of October, 2023 as against 6 and 7 days of rainfall during the month of October, 2022 and October 2021, with a cumulative rainfall of approximately 129 and 123 mm respectively during the month.
The average wind speed during the month of October, 2023 was also relatively slower and spells of absolute “still” conditions were also witnessed during the month. Despite this heavy rainfall deficit and low wind speeds, the daily avg. AQI during the month of October, 2023 at 219 has only been slightly higher than the daily avg. AQI of 210 during October, 2022.
“Delhi has also witnessed highest number of days (206) with “Good” to “Moderate” air quality (Daily Average AQI<200) during January – October 2023 as compared to the corresponding period in the previous years (barring the COVID affected 2020). “Good” to “Moderate” air quality days during this period in the previous years were only 160 in 2022, 197 in 2021, 175 in 2019 and 157 in 2018 respectively. This period in 2023 has also witnessed a remarkable reduction in daily average. PM2.5 and PM10 concentrations over the last 6 years.
The period during January-October in 2023 recorded a daily average PM2.5 concentration of about 75 µgm/m3 as against ranging from 81-95 µgm/m3 during the corresponding periods from 2017 to 2022 (barring the COVID affected 2020). Likewise, the daily average PM10 concentration in Delhi has been about 173 µgm/m3, which is much lower than a range of 182-220 µgm/m3 during the corresponding periods from 2017 to 2022 (barring the COVID affected 2020).
Delhi Environment Minister Gopal Rai has demanded that the Centre impose a strict ban on buses operating with poor-quality diesel in the National Capital Region (NCR) areas of Haryana, Uttar Pradesh and Rajasthan.
In an effort to reduce pollution levels, the Centre announced in April 2020 that all vehicles sold in India must comply with the Bharat Stage VI (BS-VI) emission standards.
