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Delhi-NCR's Struggle with Soaring Air Pollution Continues in 2023 Despite Seasonal Variations

The conclusion of 2023 witnessed Delhi-NCR grappling with elevated air pollution levels, marking a setback in the region's pursuit of cleaner air. A recent analysis by the Centre for Science and Environment (CSE) underscores that despite consistent annual improvements in PM2.5 concentrations from 2015-17, the positive trend took a halt in 2023. Unfavorable meteorological conditions played a significant role in impeding progress. While the summer and monsoon months of 2023 experienced a commendable decrease in pollution levels (14-36% cleaner compared to 2022), the winter months presented a different narrative, showcasing an increase in pollution levels (12-34%).

Air Quality In Delhi Worst In Last Six Years In November-December 2023: CSE – दिल्ली में पिछले छह वर्षों में नवंबर-दिसंबर 2023 में वायु गुणवत्ता सबसे खराब रहीः सीएसई

विश्लेषण के अनुसार ऐसा गर्मियों और मानसून के सामान्य से अधिक साफ मौसम के बावजूद हुआ और उत्तरी राज्यों में पराली से निकलने वाले धुएं में काफी कमी आई. सीएसई ने कहा कि इस साल दिल्ली के प्रदूषण को बढ़ाने वाले कारक पराली जलाने में कमी, नवंबर में अधिक बारिश और हल्की सर्दी की स्थिति के बावजूद, वार्षिक स्तर में सुधार होना चाहिए था. इसने कहा कि इसके बजाय, प्रतिकूल मौसम संबंधी स्थितियों, विशेष रूप से कम हवा की गति के कारण प्रदूषण की स्थिति खराब हो गई. दिल्ली में 2015-17 के बाद से इसके पीएम2.5 के वार्षिक स्तरों में लगातार गिरावट हो रही थी. गिरावट का यह रुझान हालांकि 2023 में रुक गया था. वर्ष 2023 (29 दिसंबर तक) के लिए दिल्ली का पीएम2.5 वार्षिक औसत 100.9 माइक्रोग्राम प्रति घन मीटर था, जो 2022 के मुकाबले दो प्रतिशत अधिक है. आंकड़ों के अनुसार, औसत वार्षिक पार्टिकुलेट मैटर (पीएम)2.5 सांद्रता 2018 में 115.8 माइक्रोग्राम प्रति घन मीटर, 2019 में 109.2, 2020 में 95.1, 2021 में 106.2, 2022 में 98.6 और 2023 में 100.9 थी. विश्लेषण से पता चला कि जहां गर्मियों में मौसम स्वच्छ होता जा रहा हैं, वहीं सर्दियां अधिक प्रदूषित होती जा रही हैं. सीएसई ने कहा कि 2023 में, गर्मी के महीने (मार्च से जून) 2022 की तुलना में काफी कम प्रदूषित (14-36 प्रतिशत) थे. इसके विपरीत, 2023 में जनवरी, नवंबर और दिसंबर के सर्दियों के महीने 2022 में इन्हीं महीनों की तुलना में बहुत अधिक प्रदूषित (12-34 प्रतिशत) थे. सीएसई ने कहा, ‘‘दिल्ली में आमतौर पर नवंबर और दिसंबर में दो बार ‘स्मॉग एपिसोड’ हुआ. वर्ष 2023 में, 24 दिसंबर तक, तीन एपिसोड हुए, और 30 दिसंबर को, दिल्ली में ‘गंभीर’ वायु गुणवत्ता का लगातार तीसरा दिन देखा गया, दिल्ली में लगातार तीसरे दिन हवा की गुणवत्ता ‘गंभीर’ रही, जो शहर में ‘स्मॉग’ की चौथी घटना है.”

Improvement In Delhi’s Annual PM2.5 Levels Since 2015-17 Halted In 2023, Says CSE Report

Delhi-NCR recorded the longest spell of ‘very poor’ or worse air quality and the maximum number of smog episodes in November and December 2023 in the last six years, according to a new analysis. The Centre for Science and Environment (CSE), an independent think-tank that analysed pollution data for Delhi-NCR, said the gradual long-term improvement in annual PM2.5 levels since 2015-17 halted in 2023. This occurred despite cleaner-than-usual summer and monsoon seasons and significantly reduced intrusion of smoke from farm fires in northern states. However, this winter witnessed unusually low surface wind speeds, trapping high levels of local pollution. Due to the impact of unusual winter levels, the overall annual levels have plateaued and worsened, reversing the gains of the long-term downward trend, the CSE said. Despite a decrease in stubble burning contributing to Delhi’s pollution this year, coupled with increased rainfall in November and milder winter conditions, the annual level should have improved. Instead, adverse meteorological conditions, specifically lower wind speeds, exacerbated the situation due to persistently high local pollution, it added. Delhi had been experiencing a consistent decline in its annual PM2.5 levels since 2015-17, with 2020 being the only outlier due to pandemic lockdowns. However, this downward trend halted in 2023. Delhi’s PM2.5 annual average for 2023 (as of December 29) stood at 100.9 micrograms per cubic metre, marking a 2 per cent increase against 2022 and 6 per cent higher than the remarkably clean 2020. The average annual PM2.5 concentrations were 115.8 microgrammes per cubic metre in 2018, 109.2 in 2019, 95.1 in 2020, 106.2 in 2021, 98.6 in 2022, and 100.9 in 2023, according to the data. The analysis revealed that while summers are becoming cleaner, winters are becoming more polluted. In 2023, the summer months (March to June) were significantly less polluted (14-36 per cent) than in 2022. Conversely, the winter months of January, November and December were much more polluted in 2023 (12-34 per cent) compared to the same months in 2022, the CSE said. It said the maximum number of smog episodes occurred in November-December 2023, surpassing the last six years’ corresponding periods. A smog episode is defined as at least three or more consecutive days with air quality in the ‘severe’ category. The CSE said, Delhi typically experiences two smog episodes in November and December. In 2023, by December 24, there were three episodes, and on December 30, Delhi was witnessing its third continuous day of ‘severe’ air quality, marking the city’s fourth smog episode. It said, Overall, November-December 2023 seems to have had the most consistently poor air compared to the last six winters, with minimal fluctuations in daily PM2.5 levels. The data indicates it was the longest spell of ‘very poor’ or worse air in the last six years.

In 2023, Delhi saw rise in PM2.5 levels: Study

Delhi's annual PM2.5 levels in 2023 were 2% higher than in 2022, reversing the city's progress in reducing particulate pollution since 2015, according to the Centre for Science and Environment. The annual concentration last year was 101 micrograms per cubic metre, higher than the national standard of 40µg/m3. The number of "good" air quality days dropped from 41 in 2022 to 24 in 2023, while days with "very poor" or worse air quality reached 107. Adverse meteorological conditions exacerbated pollution levels, highlighting the need for further emissions reductions. The Capital recorded a more polluted 2023 compared to 2022, the Centre for Science and Environment (CSE) has said in an analysis of the Capital’s annual PM 2.5 levels, which meant the city had reversed gains it had been making in reducing particulate pollution levels since records began to be kept in 2015. According to its report, the annual PM2.5 concentration last year was 101 micrograms per metre cube (µg/m3) — around 2% higher than 2022 (99µg/m3). Before that, the city recorded an annual PM2.5 concentration of 106µg/m3 in 2021, 109.2µg/m3 in 2019, and 115.8 µg/m3 in 2018. The only outlier in this trend was 2020 when the country was in a 68-day hard lockdown due to Covid-19, which helped keep the annual average PM2.5 levels to 95µg/m3, the analysis showed. “Delhi has been witnessing a gradual yet consistent decline in its annual PM2.5 levels since 2015, with 2020 being the only outlier due to massive disruption caused by pandemic lockdowns. But this downward movement stopped in 2023. Delhi’s PM2.5 annual average for 2023 was around 101 µg/m3. This was an increase of 2% compared to the 2022 annual levels and 6% higher than an exceptionally clean 2020. However, the levels were not as high as they used to be earlier – the average of 2018-22 winters is higher than that of the winter of 2023,” CSE said in its analysis.

Mercury Dips, Biomass Fire Sends Pollution Levels Up

The dipping mercury and cold-day conditions in the city have forced the poor to burn wood and roadside trash for heating or cooking, making biomass burning a major contributor to Delhi’s pollution. According to a real-time source appointment study by IIT-Kanpur (R-Aasman portal), the contribution of biomass burning in Delhi’s PM2.5 was 33% on Tuesday, 34% on Wednesday and 15% on Thursday at 6pm. Last year, DPCC had said the share of biomass burning was 24% from November 2022 to January 29, 2023. A 2021 study by IIT-Delhi said winter-haze episodes in January were highly affected by biomass burning emissions, likely from burning of wood, coal or roadside trash. “A recent analysis by the environment department, drawing on Green Delhi app complaints from December 2022 to December 2023, reveals a pressing concern: rampant biomass burning across various zones. This data, encompassing both resolved and pending complaints, paints a clear picture of hotspot clusters where household waste, garden refuse and even plastics are illegally incinerated,” stated the environment department in a letter to MCD last month. The department has identified several open burning hotspots based on complaints on Green Delhi app in the past one year. Anumita Roychowdhury, executive director, research and advocacy, Centre for Science and Environment, said, “Low-income groups who don’t have access to affordable clean energy resort to burning biomass for heating. This requires support for community-level initiatives to provide affordable alternatives. The solution is in ensuring clean energy access for all.” GRAP stage II, enforced in NCR since October 21, directs RWAs to provide electric heaters to security staff to avoid open biomass and municipal solid waste burning during the winter. However, DPCC data shows out of 1,290 RWAs contacted between October 7 and December 29, 2023, only 749 provided heaters to guards. Sunil Dahiya, analyst, Centre for Research on Energy and Clean Air, said, “There should be a proper mechanism to ensure heaters are provided to people who work outside.” DPCC data shows 1,209 notices were issued for use of coal and firewood in open eateries and a fine of Rs 6.9 lakh imposed in November while 228 notices were served in December and a penalty of Rs 10,000 imposed. While 483 notices for open burning were served in November with Rs 3.7 lakh in fines, 27 notices were issued last month with Rs 50,000 in fines. DPCC said 5,969 grievances have been received on Green Delhi app till January 1.

दिल्ली में पिछले छह वर्षों में नवंबर-दिसंबर 2023 में वायु गुणवत्ता सबसे खराब रहीः सीएसई

दिल्ली-राष्ट्रीय राजधानी क्षेत्र (एनसीआर) में पिछले छह वर्ष में नवंबर और दिसंबर 2023 में ‘बहुत खराब' या बदतर वायु गुणवत्ता का सबसे लंबा दौर और ‘स्मॉग एपिसोड' की स्थिति रही. एक नये विश्लेषण में यह जानकारी सामने आई है. ‘स्मॉग एपिसोड' की स्थिति वह होती है जब कम से कम तीन या अधिक दिन तक लगातार वायु गुणवत्ता ‘गंभीर' श्रेणी में होती है. दिल्ली-एनसीआर के प्रदूषण आंकड़े का विश्लेषण करने वाले एक स्वतंत्र थिंक-टैंक ‘सेंटर फॉर साइंस एंड एनवायरमेंट' (सीएसई) ने कहा कि 2015-17 के बाद से पीएम 2.5 के वार्षिक स्तरों में क्रमिक दीर्घकालिक सुधार 2023 में रुक गया. विश्लेषण के अनुसार ऐसा गर्मियों और मानसून के सामान्य से अधिक साफ मौसम के बावजूद हुआ और उत्तरी राज्यों में पराली से निकलने वाले धुएं में काफी कमी आई. सीएसई ने कहा कि इस साल दिल्ली के प्रदूषण को बढ़ाने वाले कारक पराली जलाने में कमी, नवंबर में अधिक बारिश और हल्की सर्दी की स्थिति के बावजूद, वार्षिक स्तर में सुधार होना चाहिए था. इसने कहा कि इसके बजाय, प्रतिकूल मौसम संबंधी स्थितियों, विशेष रूप से कम हवा की गति के कारण प्रदूषण की स्थिति खराब हो गई. दिल्ली में 2015-17 के बाद से इसके पीएम2.5 के वार्षिक स्तरों में लगातार गिरावट हो रही थी. गिरावट का यह रुझान हालांकि 2023 में रुक गया था. वर्ष 2023 (29 दिसंबर तक) के लिए दिल्ली का पीएम2.5 वार्षिक औसत 100.9 माइक्रोग्राम प्रति घन मीटर था, जो 2022 के मुकाबले दो प्रतिशत अधिक है. आंकड़ों के अनुसार, औसत वार्षिक पार्टिकुलेट मैटर (पीएम)2.5 सांद्रता 2018 में 115.8 माइक्रोग्राम प्रति घन मीटर, 2019 में 109.2, 2020 में 95.1, 2021 में 106.2, 2022 में 98.6 और 2023 में 100.9 थी. विश्लेषण से पता चला कि जहां गर्मियों में मौसम स्वच्छ होता जा रहा हैं, वहीं सर्दियां अधिक प्रदूषित होती जा रही हैं. सीएसई ने कहा कि 2023 में, गर्मी के महीने (मार्च से जून) 2022 की तुलना में काफी कम प्रदूषित (14-36 प्रतिशत) थे. इसके विपरीत, 2023 में जनवरी, नवंबर और दिसंबर के सर्दियों के महीने 2022 में इन्हीं महीनों की तुलना में बहुत अधिक प्रदूषित (12-34 प्रतिशत) थे. सीएसई ने कहा, ‘‘दिल्ली में आमतौर पर नवंबर और दिसंबर में दो बार ‘स्मॉग एपिसोड' हुआ. वर्ष 2023 में, 24 दिसंबर तक, तीन एपिसोड हुए, और 30 दिसंबर को, दिल्ली में ‘गंभीर' वायु गुणवत्ता का लगातार तीसरा दिन देखा गया, दिल्ली में लगातार तीसरे दिन हवा की गुणवत्ता ‘गंभीर' रही, जो शहर में ‘स्मॉग' की चौथी घटना है.''

Improvement in Delhi's PM2.5 levels since 2015-17 halted in 2023: CSE

Delhi-NCR recorded the longest spell of 'very poor' or worse air quality and the maximum number of smog episodes in November and December 2023 in the last six years, according to a new analysis. The Centre for Science and Environment (CSE), an independent think-tank that analysed pollution data for Delhi-NCR, said the gradual long-term improvement in annual PM2.5 levels since 2015-17 halted in 2023. This occurred despite cleaner-than-usual summer and monsoon seasons and significantly reduced intrusion of smoke from farm fires in northern states. However, this winter witnessed unusually low surface wind speeds, trapping high levels of local pollution. Due to the impact of unusual winter levels, the overall annual levels have plateaued and worsened, reversing the gains of the long-term downward trend, the CSE said. Despite a decrease in stubble burning contributing to Delhi's pollution this year, coupled with increased rainfall in November and milder winter conditions, the annual level should have improved. Instead, adverse meteorological conditions, specifically lower wind speeds, exacerbated the situation due to persistently high local pollution, it added. Delhi had been experiencing a consistent decline in its annual PM2.5 levels since 2015-17, with 2020 being the only outlier due to pandemic lockdowns. However, this downward trend halted in 2023. Delhi's PM2.5 annual average for 2023 (as of December 29) stood at 100.9 micrograms per cubic metre, marking a 2 per cent increase against 2022 and 6 per cent higher than the remarkably clean 2020. The average annual PM2.5 concentrations were 115.8 microgrammes per cubic metre in 2018, 109.2 in 2019, 95.1 in 2020, 106.2 in 2021, 98.6 in 2022, and 100.9 in 2023, according to the data. The analysis revealed that while summers are becoming cleaner, winters are becoming more polluted. In 2023, the summer months (March to June) were significantly less polluted (14-36 per cent) than in 2022. Conversely, the winter months of January, November and December were much more polluted in 2023 (12-34 per cent) compared to the same months in 2022, the CSE said. It said the maximum number of smog episodes occurred in November-December 2023, surpassing the last six years' corresponding periods.

This winter, Delhi saw highest number of smog episodes in 6 years

Despite lower levels of smoke from farm fires impacting Delhi, this winter saw the highest number of smog episodes in the national capital in six years with “unusually low surface wind speeds” that trapped local pollution levels that were already high, according to an analysis by the Centre for Science and Environment (CSE). The average surface wind speed in Delhi in November was 9.8 m/s, the lowest in the last six years, going by the analysis, which identifies this as the “driving factor” for the poor air quality this winter. This is because low wind speed prevents pollutants from dispersing horizontally even as the inversion phenomenon in winter already prevents vertical dispersion of pollutants, according to the analysis. Inversion in winter is when cold air close to the surface of the earth remains trapped by a lid of warm air above it. In contrast, the average wind speed in November last year was 12.4 m/s, while it was 11 m/s in November 2021. The analysis has used data on wind speed from the India Meteorological Department. “We are not really sure why wind speed is lower than usual, but it has remained low all of November and December. With both vertical and horizontal movement stopping, pollutants have remained stuck. So, even with little smoke from farm fires coming in and winter temperatures not being as cold as they were earlier, we still saw high pollution levels this winter. Much smoke from farm fires has not reached Delhi because of the winds not being favourable. Data from NASA shows that farm fires reported this year were similar to what was reported last year,” said Avikal Somvanshi from CSE, who was part of the team that carried out the analysis. The trapping of local pollution “has made this winter exceptionally bad despite lesser smoke from farm stubble fires,” the analysis noted. It estimates the contribution of farm fires to PM2.5 levels in Delhi in November to be 1.48 metric tonnes, which was found to be the lowest in the past six years. This contribution was 3 metric tonnes last year and 5.68 metric tonnes in November 2021. The lower contribution from farm fires notwithstanding, this year, the national capital recorded its most polluted winter in six years in terms of smog episodes – when the air quality has remained in the ‘severe’ category in terms of PM2.5 levels for at least three consecutive days. This year, there have been three such episodes by December 24, and a fourth one at the end of December, going by the analysis.

After seven years, 2023 bucks the declining trend in PM2.5 in Delhi

NEW DELHI: The gradual and consistent decline in the city's annual PM2.5 levels since 2015-17 was interrupted in 2023, according to the Centre for Science and Environment. Delhi's annual PM2.5 average for 2023 till December 29 stood at 100.9 micrograms per cubic metre, an increase of 2% from 2022 6% from the exceptionally clean 2020. Delhi pollution The analysis by CSE found that in 2023, 151 days met the National Ambient Air Quality Standards. This was similar to the trend in 2021 and second only to the lockdown year of 2020 when 174 days had met the quality standard. In 2022, only 117 days had met the norms. Almost all of these cleaner days were recorded in the summer and monsoon seasons, said CSE. Track the pollution level in your city Despite the days meeting the quality norms in 2023, there was a significant fall in the number of 'good' air days when the pollution levels were 50% below the standard that year, with 24 such days against 41 in 2022. Between October 1 and December 29 in 2023, there were only three days of 'satisfactory' air quality and no 'good' air day. There were more days in these categories in the same period in the previous two years. According to CSE, Delhi also suffered the highest number of smog episodes of the past six winters in the current season. While there are usually two smog episodes (defined as at least three or more continuous days of 'severe' pollution) in the months of November and December, there were three in 2023 by December 24 and the fourth by December 30. "This was the highest number of smog episodes observed in a season in the past six winters," said a CSE statement. "Overall, the 2023 winter seems to have had the most consistent bad air in the last six winters, with minimal fluctuations in daily PM2.5 levels. The data indicates that this was the longest spell of 'very poor' or 'worse' air in the last six years." Anumita Roychowdhury, executive director, research and advocacy, CSE, said, "Due to the impact of the unusual winter levels, the overall annual pollution concentrations plateaued and even worsened, undoing the gains of the long-term downward trend. With the contribution of stubble burning to Delhi's pollution going down this year because of rain in November and less severe cold conditions, the annual PM2.5 level should have improved." She explained that the worsening of meteorological conditions - mostly, low wind speed - left pollution at high levels. Avikal Somvanshi, senior programme manager, Urban Lab, CSE, said, "Sustained action is required on reducing vehicular emissions, with a massive scaling up of the zero-emission electric vehicle programme and an efficient public transport strategy. There has to be a clean fuel transition in all segments of industries, with stringent compliance with emissions targets and replacement of solid fuels in households and eateries. Waste burning must be eliminated and strong measures taken in the construction sector."

Improvement in Delhi's annual PM2.5 levels since 2015-17 halted in 2023, says CSE report

Delhi-NCR recorded the longest spell of very poor or worse air quality and the maximum number of smog episodes in November and December 2023 in the last six years, according to a new analysis.The Centre for Science and Environment CSE, an independent think-tank that analysed pollution data for Delhi-NCR, said the gradual long-term improvement in annual PM2.5 levels since 2015-17 halted in 2023.This occurred despite cleaner-than-usual summer and monsoon seasons and significantly reduced intrusion of smoke from farm fires in northern states. The Centre for Science and Environment (CSE), an independent think-tank that analysed pollution data for Delhi-NCR, said the gradual long-term improvement in annual PM2.5 levels since 2015-17 halted in 2023. This occurred despite cleaner-than-usual summer and monsoon seasons and significantly reduced intrusion of smoke from farm fires in northern states. However, this winter witnessed unusually low surface wind speeds, trapping high levels of local pollution. Due to the impact of unusual winter levels, the overall annual levels have plateaued and worsened, reversing the gains of the long-term downward trend, the CSE said. Despite a decrease in stubble burning contributing to Delhi's pollution this year, coupled with increased rainfall in November and milder winter conditions, the annual level should have improved. Instead, adverse meteorological conditions, specifically lower wind speeds, exacerbated the situation due to persistently high local pollution, it added. Delhi had been experiencing a consistent decline in its annual PM2.5 levels since 2015-17, with 2020 being the only outlier due to pandemic lockdowns. However, this downward trend halted in 2023. Delhi's PM2.5 annual average for 2023 (as of December 29) stood at 100.9 micrograms per cubic metre, marking a 2 per cent increase against 2022 and 6 per cent higher than the remarkably clean 2020. The average annual PM2.5 concentrations were 115.8 microgrammes per cubic metre in 2018, 109.2 in 2019, 95.1 in 2020, 106.2 in 2021, 98.6 in 2022, and 100.9 in 2023, according to the data. The analysis revealed that while summers are becoming cleaner, winters are becoming more polluted. In 2023, the summer months (March to June) were significantly less polluted (14-36 per cent) than in 2022. Conversely, the winter months of January, November and December were much more polluted in 2023 (12-34 per cent) compared to the same months in 2022, the CSE said. It said the maximum number of smog episodes occurred in November-December 2023, surpassing the last six years' corresponding periods. A smog episode is defined as at least three or more consecutive days with air quality in the 'severe' category. ''Delhi typically experiences two smog episodes in November and December. In 2023, by December 24, there were three episodes, and on December 30, Delhi was witnessing its third continuous day of 'severe' air quality, marking the city's fourth smog episode,'' the CSE said. ''Overall, November-December 2023 seems to have had the most consistently poor air compared to the last six winters, with minimal fluctuations in daily PM2.5 levels. The data indicates it was the longest spell of 'very poor' or worse air in the last six years,'' it said.

Improvement in Delhi's annual PM2.5 levels since 2015-17 halted in 2023, says CSE report

Delhi-NCR recorded the longest spell of 'very poor' or worse air quality and the maximum number of smog episodes in November and December 2023 in the last six years, according to a new analysis. The Centre for Science and Environment (CSE), an independent think-tank that analysed pollution data for Delhi-NCR, said the gradual long-term improvement in annual PM2.5 levels since 2015-17 halted in 2023. This occurred despite cleaner-than-usual summer and monsoon seasons and significantly reduced intrusion of smoke from farm fires in northern states. However, this winter witnessed unusually low surface wind speeds, trapping high levels of local pollution. Due to the impact of unusual winter levels, the overall annual levels have plateaued and worsened, reversing the gains of the long-term downward trend, the CSE said. Despite a decrease in stubble burning contributing to Delhi's pollution this year, coupled with increased rainfall in November and milder winter conditions, the annual level should have improved. Instead, adverse meteorological conditions, specifically lower wind speeds, exacerbated the situation due to persistently high local pollution, it added. Delhi had been experiencing a consistent decline in its annual PM2.5 levels since 2015-17, with 2020 being the only outlier due to pandemic lockdowns. However, this downward trend halted in 2023. Delhi's PM2.5 annual average for 2023 (as of December 29) stood at 100.9 micrograms per cubic metre, marking a 2 per cent increase against 2022 and 6 per cent higher than the remarkably clean 2020.

Improvement in Delhi’s annual PM2.5 levels since 2015-17 halted in 2023, says CSE report

Delhi-NCR recorded the longest spell of ‘very poor’ or worse air quality and the maximum number of smog episodes in November and December 2023 in the last six years, according to a new analysis. The Centre for Science and Environment (CSE), an independent think-tank that analysed pollution data for Delhi-NCR, said the gradual long-term improvement in annual PM2.5 levels since 2015-17 halted in 2023. This occurred despite cleaner-than-usual summer and monsoon seasons and significantly reduced intrusion of smoke from farm fires in northern states. However, this winter witnessed unusually low surface wind speeds, trapping high levels of local pollution. Due to the impact of unusual winter levels, the overall annual levels have plateaued and worsened, reversing the gains of the long-term downward trend, the CSE said. Despite a decrease in stubble burning contributing to Delhi’s pollution this year, coupled with increased rainfall in November and milder winter conditions, the annual level should have improved. Instead, adverse meteorological conditions, specifically lower wind speeds, exacerbated the situation due to persistently high local pollution, it added. Delhi had been experiencing a consistent decline in its annual PM2.5 levels since 2015-17, with 2020 being the only outlier due to pandemic lockdowns. However, this downward trend halted in 2023. Delhi’s PM2.5 annual average for 2023 (as of December 29) stood at 100.9 micrograms per cubic metre, marking a 2 per cent increase against 2022 and 6 per cent higher than the remarkably clean 2020. The average annual PM2.5 concentrations were 115.8 microgrammes per cubic metre in 2018, 109.2 in 2019, 95.1 in 2020, 106.2 in 2021, 98.6 in 2022, and 100.9 in 2023, according to the data. The analysis revealed that while summers are becoming cleaner, winters are becoming more polluted. In 2023, the summer months (March to June) were significantly less polluted (14-36 per cent) than in 2022. Conversely, the winter months of January, November and December were much more polluted in 2023 (12-34 per cent) compared to the same months in 2022, the CSE said. It said the maximum number of smog episodes occurred in November-December 2023, surpassing the last six years’ corresponding periods. A smog episode is defined as at least three or more consecutive days with air quality in the ‘severe’ category. “Delhi typically experiences two smog episodes in November and December. In 2023, by December 24, there were three episodes, and on December 30, Delhi was witnessing its third continuous day of ‘severe’ air quality, marking the city’s fourth smog episode,” the CSE said. “Overall, November-December 2023 seems to have had the most consistently poor air compared to the last six winters, with minimal fluctuations in daily PM2.5 levels. The data indicates it was the longest spell of ‘very poor’ or worse air in the last six years,” it said. PTI GVS SZM

Improvement in Delhi's annual PM2.5 levels since 2015-17 halted in 2023, says CSE report

NEW DELHI: Delhi-NCR recorded the longest spell of 'very poor' or worse air quality and the maximum number of smog episodes in November and December 2023 in the last six years, according to a new analysis. The Centre for Science and Environment (CSE), an independent think-tank that analysed pollution data for Delhi-NCR, said the gradual long-term improvement in annual PM2.5 levels since 2015-17 halted in 2023. This occurred despite cleaner-than-usual summer and monsoon seasons and significantly reduced intrusion of smoke from farm fires in northern states. However, this winter witnessed unusually low surface wind speeds, trapping high levels of local pollution.

City records longest spell of very poor or worse AQI in last six years

The National Capital Region recorded the longest spell of ‘very poor’ or worse air quality and the maximum number of smog episodes in November and December 2023 in the last six years, according to a new analysis.The Centre for Science and Environment (CSE), an independent think-tank that analysed pollution data for Delhi-NCR, said the gradual long-term improvement in annual PM2.5 levels since 2015-17 halted in 2023. This occurred despite cleaner-than-usual summer and monsoon seasons and significantly reduced intrusion of smoke from farm fires in northern states. However, this winter witnessed unusually low surface wind speeds, trapping high levels of local pollution. Due to the impact of unusual winter levels, the overall annual levels have plateaued and worsened, reversing the gains of the long-term downward trend, the CSE said. Despite a decrease in stubble burning contributing to Delhi’s pollution this year, coupled with increased rainfall in November and milder winter conditions, the annual level should have improved. Instead, adverse meteorological conditions, specifically lower wind speeds, exacerbated the situation due to persistently high local pollution, it added. Delhi had been experiencing a consistent decline in its annual PM2.5 levels since 2015-17, with 2020 being the only outlier due to pandemic lockdowns. However, this downward trend halted in 2023. Delhi’s PM2.5 annual average for 2023 (as of December 29) stood at 100.9 micrograms per cubic metre, marking a 2 per cent increase against 2022 and 6 per cent higher than the remarkably clean 2020. The average annual PM2.5 concentrations were 115.8 microgrammes per cubic metre in 2018, 109.2 in 2019, 95.1 in 2020, 106.2 in 2021, 98.6 in 2022, and 100.9 in 2023, according to the data. The analysis revealed that while summers are becoming cleaner, winters are becoming more polluted. In 2023, the summer months (March to June) were significantly less polluted (14-36 per cent) than in 2022. Conversely, the winter months of January, November and December were much more polluted in 2023 (12-34 per cent) compared to the same months in 2022, the CSE said. It said the maximum number of smog episodes occurred in November-December 2023, surpassing the last six years’ corresponding periods. A smog episode is defined as at least three or more consecutive days with air quality in the ‘severe’ category. “Delhi typically experiences two smog episodes in November and December. In 2023, by December 24, there were three episodes, and on December 30, Delhi was witnessing its third continuous day of ‘severe’ air quality, marking the city’s fourth smog episode,” the CSE said. “Overall, November-December 2023 seems to have had the most consistently poor air compared to the last six winters, with minimal fluctuations in daily PM2.5 levels. The data indicates it was the longest spell of ‘very poor’ or worse air in the last six years,” it said.

Improvements in PM 2.5 levels in Delhi since 2015-2017 halted in 2023: Centre for Science and Environment

According to a study by Centre for Science and Environment (CSE), a public interest research and advocacy organisation on environment based in New Delhi, the gradual long-term improvement in annual PM2.5 levels in Delhi NCR since 2015-17 halted in 2023. According to the CSE study, Delhi-NCR recorded the longest spell of ‘very poor’ or worse air quality and the maximum number of smog episodes in November and December 2023 in the last six years. In a press release, CSE said: “ The year 2023’s winter months were a period when the region of Delhi-NCR slipped back into the abyss of high pollution levels – despite having seen a gradual long-term improvement in annual PM2.5 concentrations since 2015-17. The forward march towards cleaner air and clearer skies came to a grinding halt in 2023. The region witnessed cleaner-than-usual summer and monsoon seasons, and much lower ingress of smoke from farm stubble fires in the northern states. But unusually low surface wind speed in winter meant that local pollution, which was already quite high, was trapped. This led to the spike in pollution levels.” The CSE study said that highest number of smog episodes were witnessed in last 6 winters, “ Delhi usually experiences two smog episodes (a smog episode is defined as at least three or more minimum continuous days with air quality inthe ‘severe’ category) in the months of November and December. In 2023, there were three episodes by December 24; on December 30, Delhi was reeling under its third day of continuous ‘severe’air quality, which was turning into the city’s fourth smog episode. This was the highest number of smog episodes observed in a season in last six winters. Overall, 2023 winter seems to have had the most consistently bad air compared to the last six winters, with minimal fluctuations in daily PM2.5 levels. Data indicates that it was the longest spell of ‘very poor’ or ‘worse’ air in last six years,” CSE said.

Last year, air quality was better in summer: Report

The air in Delhi-NCR was more polluted during the winter season in 2023 as compared to the summer months of the year. This was stated in an analysis report that was released by the Centre for Science and Environment (CSE) on Thursday. The report mentioned that the region witnessed cleaner summer and monsoon seasons and the ingress of smoke from stubble fires in the northern states was much lower in the warmer months. However, pollutants remained trapped in the atmosphere during the winter, leading to a spike in pollution levels. “The summer months of March, April, May and June, 2023, were significantly less polluted as compared to the corresponding period in 2022. However, winter months of January, November and December, 2023, witnessed higher polluted levels than those of 2022,” stated the CSE. It said the region slipped back into the abyss of high pollution levels in the winter of 2023, despite recording a gradual but long-term improvement in the annual PM2.5 concentrations since 2015-17. It added that the forward march towards cleaner air and clearer skies came to a grinding halt in 2023.