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CSE report finds high ground-level ozone in 10 Indian metros between 2020-2024, ‘green areas’ hotspots

Delhi saw 176 days in summer 2024, between 1 April and 18 July, where ground ozone levels exceeded national air quality standards, according to a new report by the Centre for Science and Environment (CSE), a New Delhi-based think tank. Released Tuesday, the CSE report on ground-level ozone is based on a nationwide analysis which found that 10 metropolitan cities saw an increase in daily maximum levels of ozone between 2020 and 2024. The report found that ozone levels also increased in non-metropolitan areas compared to last year, and persisted beyond summer months which, it said, was a concerning trend. Ozone pollution is a very specific phenomenon — the presence of the gas in the stratosphere is considered healthy, but ground-level ozone causes health issues for humans. The CSE report

દિલ્હી, મુંબઈ, બેંગલુરુ માટે ઓઝોન સ્તરનો ખતરો, CSE રિપોર્ટમાં આવ્યો ચોંકાવનારો ખુલાસો

ભારતના મોટા શહેરો માટે વાયુ પ્રદૂષણનો ખતરો હવે જીવલેણ બની રહ્યો છે. દર વર્ષે દિલ્હી એનસીઆર અને અન્ય મોટા શહેરોમાં રહેતા લોકો આ ભયના કારણે ગંભીર બીમારીઓનો ભોગ બને છે. સેન્ટર ફોર સાયન્સ એન્ડ એન્વાયર્નમેન્ટ (CSE) એ હવે આ અંગે નવો અહેવાલ પ્રકાશિત કર્યો છે. આ રિપોર્ટમાં તેમણે ખુલાસો કર્યો છે કે કેવી રીતે ઓઝોન ગેસ આ શહેરોની હવાને વધુ ઝેરી બનાવી રહ્યો છે. ચાલો તમને આ લેખમાં આ અહેવાલ વિશે વિગતવાર જણાવીએ. આ શહેરોમાં ઓઝોન સ્તર જોખમમાં છે દિલ્હી NCR, બેંગલુરુ, ચેન્નઈ, કોલકાતા, મુંબઈ અને પુણે તેમજ ગ્રેટર અમદાવાદ, ગ્રેટર હૈદરાબાદ, ગ્રેટર જયપુર અને ગ્રેટર લખનૌમાં સ્થિતિ ચિંતાજનક છે. વાસ્તવમાં, દિલ્હી સ્થિત થિંક ટેન્ક સેન્ટર ફોર સાયન્સ એન્ડ એન્વાયર્નમેન્ટ (CSE)ના નવા અહેવાલ મુજબ, આ ભારતીય શહેરોમાં ઓઝોન પ્રદૂષણના સ્તરમાં ચિંતાજનક વધારો થયો છે. ખાસ કરીને આ વર્ષના ઉનાળા દરમિયાન, ભારતના 20 મુખ્ય શહેરી વિસ્તારોમાં જમીન સ્તરે ઓઝોન ગેસનું સ્તર નોંધપાત્ર રીતે વધ્યું છે. જેના કારણે આ વિસ્તારોની હવા પહેલા કરતા વધુ ઝેરી બની ગઈ છે. આ તમામ શહેરો પૈકી દિલ્હી સૌથી વધુ પ્રભાવિત થયું છે. ઓઝોન સ્તર સામાન્ય કરતા વધારે છે CSEના નવા રિપોર્ટ અનુસાર, દિલ્હી NCR સહિત તમામ 10 મોટા શહેરોમાં ઓઝોન ગેસનું સ્તર સામાન્ય કરતા વધારે છે. જ્યારે દિલ્હી-એનસીઆરમાં 176 દિવસ સુધી ગ્રાઉન્ડ લેવલ ઓઝોન ગેસનું સ્તર સામાન્યથી ઉપર રહ્યું, જ્યારે મુંબઈ અને પુણેમાં 138 દિવસ સુધી સ્થિતિ સમાન રહી. જયપુરમાં 126 દિવસ, હૈદરાબાદમાં 86, કોલકાતામાં 63, બેંગલુરુમાં 59, લખનૌમાં 49 અને અમદાવાદમાં 41 દિવસ સુધી ઓઝોન ગેસનું સ્તર અસામાન્ય હતું. જ્યારે, આવા દિવસોની સૌથી ઓછી સંખ્યા ચેન્નાઈમાં લગભગ 9 દિવસ નોંધાઈ હતી. આ વર્ષે આ સમસ્યા વધુ વધી છે CSEના આ નવા રિપોર્ટમાં એ વાતનો પણ ખુલાસો થયો છે કે વર્ષ 2024માં ઓઝોન પ્રદૂષણની વધતી જતી સમસ્યા 2020માં લોકડાઉન દરમિયાન ઉનાળામાં ઊભી થયેલી સમસ્યા કરતાં વધુ વધી છે. આજે સ્થિતિ એવી છે કે વધતા પ્રદુષણની સમસ્યા હવે માત્ર મોટા શહેરો પુરતી સીમિત નથી રહી પરંતુ નાના શહેરો પણ વધતા પ્રદૂષણની સમસ્યાનો સામનો કરી રહ્યા છે. આ CSE રિપોર્ટ અનુસાર, આ વર્ષે 10 માંથી 7 શહેરોમાં ઓઝોનનું સ્તર ગત વર્ષ કરતા વધુ દિવસોએ વધારે રહ્યું છે. અમદાવાદ જેવા નાના શહેરમાં સૌથી મોટો ઉછાળો આવ્યો છે, જ્યાં ઓઝોન 4,000 ટકા વધ્યો છે. જ્યારે પુણેમાં 500 ટકા, જયપુરમાં 152 ટકા અને હૈદરાબાદમાં 115 ટકાનો વધારો નોંધાયો હતો.

OZONE POLLUTION ACROSS INDIA

WHY IN NEWS? A recent study by the Delhi-based think tank Centre for Science and Environment (CSE) has uncovered a concerning trend: ground-level ozone pollution is increasing in major cities across India. This invisible gas, distinct from the well-known fine particulate matter (PM2.5), poses a significant health risk, especially for individuals with respiratory issues. The report titled “Air Quality Tracker: An Invisible Threat” was released on August 6, 2024. The researchers examined metropolitan areas including Bengaluru (Karnataka), Chennai (Tamil Nadu), Kolkata (West Bengal), Mumbai, and Pune (Maharashtra). They also analyzed data for the Delhi-National Capital Region, Greater Ahmedabad (Gujarat), Greater Hyderabad (Telangana), Greater Jaipur (Rajasthan), and Greater Lucknow (Uttar Pradesh). All 10 areas studied exceeded the national ozone standard, with Delhi being the most affected. The report also found that smaller cities like Ahmedabad and Pune are experiencing a particularly rapid increase in ozone pollution. What is Ozone? Ozone (O3) is a colourless, reactive oxidant gas, and it is a major component of atmospheric smog. Ozone exists in both the Earth’s upper atmosphere and its surface, is composed of three oxygen atoms. Its environmental and health impact depends on its location in the atmosphere, leading to either positive or negative effects. Even at low concentrations, ozone, a pale blue gas, can be hazardous and explosive. In India, the ozone issue is primarily linked to sunny weather since sunlight directly influences ground-level ozone formation. Photochemical processes are facilitated by heat catalysis, resulting in higher ozone concentrations during summertime. Formation of Ozone:

दिल्ली-एनसीआर में जमीनी स्तर पर ओजोन सबसे ज्यादा

सेंटर फॉर साइंस एंड एनवायरनमेंट (सीएसई) द्वारा जारी एक रिसर्च रिपोर्ट के मुताबिक दिल्ली-एनसीआर देश भर के उन 10 शहरों की सूची में सबसे ऊपर है, जिनमें जमीनी स्तर पर ओजोन गैस (ओ3) की मात्रा बेहद बढ़ी हुई पाई गई है. रिपोर्ट के मुताबिक जनवरी 1 से जुलाई 18 तक, यानी कि 200 दिनों में से, 176 दिनों में दिल्ली एनसीआर में जमीनी ओजोन की मात्रा बढ़ी हुई थी. दूसरे स्थान पर रहे मुंबई और पुणे में 200 में से 138 दिनों में यह मात्रा ज्यादा पाई

After sunset: Why ozone scare is real for Delhi and its neighbours

An analysis by the Centre for Science and Environment says that in summer this year, the ground-level ozone in the air increased in 10 metropolitan areas of India, with Delhi being the most affected. So far, Delhi-NCR has recorded 176 days of exceedance during the study period, followed by Mumbai and Pune with 138 days.CSE said ground-level ozone usually exceeds the safety standard on all days of summer in some locations in Delhi-NCR every year. This year the number of stations exceeding the standard across core NCR has been 17.6, the highest in the last five years. On average, only 9.4 stations exceeded the standard daily in the previous summers. It was 14.6 stations in the 2020 summer. The report also said ground-level ozone should ideally be negligible in the night air, but all 10 metropolitan areas saw a rare phenomenon of elevated ozone level after sunset. The study considered ozone in excess when the hourly concentration exceeded 100 micrograms per cubic metre between 10pm and 2am at any station. Mumbai-MMR reported the most instances of night-time ground-level ozone with 171 nights of exceedance, followed by Delhi-NCR (161) and Pune (131). Ground-level ozone, a highly reactive gas, has serious health consequences. “Those with respiratory conditions, asthma and chronic obstructive pulmonary disease, children with premature lungs and older adults can face serious risks. The gas can inflame and damage airways, make lungs susceptible to infection, aggravate asthma, emphysema and chronic bronchitis and increase the frequency of asthma attacks,” said Anumita Roychowdhury, executive director, research and advocacy, CSE. Not only has the spatial spread in Delhi-NCR increased this year, but also the duration. This summer, at the stations which reported exceedance, the high levels lasted on average 13.9 hours, the highest since the pandemic summer of 2020. Even upscale and green neighbourhoods were affected, including Dr Karni Singh Shooting Range and Lodhi Colony. “This is consistent with the science that ozone drifts and gathers in areas where a comparatively lower amount of gaseous pollutants are present. Thus, relatively cleaner areas, including urban peripheries, can have comparatively higher ozone concentrations,” explained Roychowdhury. Avikal Somvanshi, programme manager, Urban Lab, CSE, who led the study, said, “Even though ground-level ozone exceedance is assumed to be at its worst during summer months, data from the 10 metropolitan areas analysed in our study shows that it is a year-long problem.” The 2020 State of Global Air report states that age-standardised rates of death attributable to ground-level ozone are among the highest in India. The seasonal eight-hour daily maximum concentrations recorded among the highest increases — around 17% — in India between 2010 and 2017. CSE suggested that the country should develop a robust public information and dissemination system to alert the public wherever ozone build-up takes place.

Ozone scare in major Indian cities in 2024 summer, finds new CSE study

A new nation-wide analysis by Centre for Science and Environment (CSE) says that in the summer of 2024, the levels of ground-level ozone in the air went up in the 10 major metropolitan areas of India. These areas and cities include Bengaluru Metropolitan Area (Karnataka), Chennai Metropolitan Area (Tamil Nadu), Delhi-NCR, Greater Ahmedabad (Gujarat), Greater Hyderabad (Telangana), Greater Jaipur (Rajasthan), Kolkata Metropolitan Area (West Bengal), Greater Lucknow (Uttar Pradesh), Mumbai Metropolitan Region (Maharashtra) and Pune Metropolitan Region (Maharashtra). Says Anumita Roychowdhury, executive director, research and advocacy, CSE: “Ground-level ozone, a highly reactive gas, has serious health consequences. Those with respiratory conditions, asthma and chronic obstructive pulmonary disease – as well as children with premature lungs and older adults — are at serious risk. This can inflame and damage airways, make lungs susceptible to infection, aggravate asthma, emphysema, and chronic bronchitis and increase the frequency of asthma attacks leading to increased hospitalisation.” The 2020 State of Global Air report states that age-standardised rates of death attributable to ground-level ozone is among the highest in India. The seasonal eight-hour daily maximum concentrations have recorded one of the highest increases in India between 2010 and 2017 – about 17 per cent. Ozone needs special attention — ground-level ozone is not directly emitted from any source. It is produced from complex interaction between nitrogen oxides (NOx) and volatile organic compounds (VOCs) that are emitted from vehicles, power plants, factories, and other combustion sources and undergo cyclic reactions in the presence of sunlight to generate ground-level ozone. VOCs can also be emitted from natural sources, such as plants. Roychowdhury points out that as the National Clean Air Programme (NCAP) gears up for its second phase, “its reform agenda has to address the multi-pollutant crisis and the combined threat from PM2.5, ozone, nitrogen oxides and other gases. Global experience shows that there is usually a trade-off — as particulate pollution gets reduced, the problem of NOx and ground-level ozone increases. This requires significant tightening of the regulatory benchmark for ozone to address the toxic emisisons from industry, vehicles, households and open burning”. “Moreover, ozone not only builds up in metropolitan areas but also drifts long distances to form a regional pollutant that makes both local and regional action necessary,” she adds. According to Avikal Somvanshi, programme manager, Urban Lab, CSE, who has led the CSE study, “in 2024, we have found that the geographical spread of the problem is much wider than what we had seen in the lockdown summer of 2020 in most metropolitan areas. This time’s toxic build-up has lasted longer in locations affected by the problem. Even the smaller metropolitan areas have witnessed rapid increase. In metropolitan areas in the south and western coastal belt, the problem is not limited only to the summer months.” Adds Somvanshi: “Inadequate monitoring, limited data and inappropriate methods of trend analysis have weakened the understanding of this growing public health hazard. The complex chemistry of ground-level ozone makes it a difficult pollutant to track and mitigate. Due to its toxic nature, ozone’s national ambient air quality standard has been set for only short-term exposures (one-hour and eight-hour averages), and compliance is measured by the number of days that exceed the standards. This requires early action.” The investigation methodology This assessment has traced trends during summer (April 1-July 18). The data covered is from 2020 to 2024. The analysis is based on publicly available granular real time data (15-minute averages) from the Central Pollution Control Board’s (CPCB) official online portal, the Central Control Room for Air Quality Management. The data has been captured from official stations under the Continuous Ambient Air Quality Monitoring System (CAAQMS) spread across 10 metropolitan regions. The station break-up is as follows: Delhi-NCR (58 stations), Mumbai Metropolitan Region (48), Kolkata Metropolitan Area (10), Greater Hyderabad (14), Bengaluru Metropolitan Area (14), Chennai Metropolitan Area (nine), Pune Metropolitan Region (15), Greater Ahmedabad (10), Greater Lucknow (seven) and Greater Jaipur (six). Sharanjeet Kaur, programme officer, Urban Lab, CSE, says: “This analysis has considered station-level trends in terms of number of days exceeding the eight -hour standard over time. The study has considered global good practices and taken on board the USEPA approach of computing eight-hour averages for a day and then checking for the maximum value among them to capture the daily ozone pollution level. The key highlights of the CSE analysis Monitoring of ozone and method of its trend analysis need to improve to inform policy: the compliance method as set by the CPCB requires that the ozone standards are met for 98 per cent of the time in the year. It may exceed the limits on two per cent of the days in a year, but not on two consecutive days of monitoring. Says Kaur: “In other words, there should not be more than eight days in a year when the ozone standard is breeched, and none of those allowed exceedances can be on two consecutive days.” Somvanshi explains: “The standard practice of the CPCB to average out the data of all stations in the city to determine daily AQI does not work for ground-level ozone as it is a short-lived and hyper-localised pollutant. A city-wide average concentration level over an extended time frame does not indicate the severity of the problem and health implications from local build-up and exposure for people living in hotspots.” Adds Somvanshi: “While analysing the data, it was also noted that the ozone data available on the CPCB portal never exceeds 200 microgramme per cubic metre (μg/m3) while data for the corresponding time provided by the Delhi Pollution Control Committee may show higher levels. Due to this capping of data, it is not possible to understand the nature of peaking in the city. This needs to be addressed as there are two sets of standards for ozone – an eight-hourly standard of 100 μg/m3 and a one-hourly standard of 180 μg/m3. Capping makes assessment of one-hourly standard challenging.” Ground-level ozone exceedance has been reported in all 10 metropolitan areas, with Delhi being the most affected: This year, so far, Delhi-NCR has recorded 176 days of exceedances during the study period. Mumbai-MMR and Pune are tied at the second spot with 138 days of exceedance each. Jaipur recorded an exceedance on 126 days; Hyderabad, on 86 days; Kolkata-KMA, 63 days; Bengaluru, 59 days; Lucknow, 49 days; and Ahmedabad, 41 days. The least number of exceedance was recorded in Chennai: a mere nine days. Ground-level ozone exceedance is more frequent during summer for Delhi-NCR, Jaipur, Kolkata-KMA, Lucknow, Ahmedabad and Chennai. In Mumbai-MMR, Pune, Hyderabad, and Bengalure, more exceedances were reported during January-March than during the summer (April-July). A massive increase in ground-level ozone exceedance is reported in smaller metropolitan areas: Comparing the number of exceedances this year so far with the same period from last year shows an increase in seven out of 10 metropolitan areas analysed in this study. The smaller metropolitan areas have had the biggest jumps, with Ahmedabad registering a 4,000 per cent rise in number of exceedances. Pune follows with 500 per cent, and Jaipur had a 152 per cent increase. Hyderabad registerd a 115 per cent rise in number of exceedance days; Mumbai-MMR and Bengaluru saw an 18 per cent and 1 per cent increase, respectively. Less than 5 per cent change has been noted in Delhi-NCR and Lucknow. Meanwhile, Kolkata-KMA and Chennai have seen a drop in the number of exceedances by 19 per cent and 40 per cent, respectively. Summer ground-level ozone peak is dangerously high in all 10 metropolitan areas: Even though the number of exceedance days is highest among Delhi-NCR and Mumbai-MMR (partly because they have highest number of stations), but from regional average concentration and peak level perspective, Jaipur air is more toxic. The regional average of Jaipur for April 1 to July 15 is 81.2 µg/m3 compared to Delhi-NCR’s 73.3 µg/m3 and Mumbai-MMR’s 34.8 µg/m3. Chennai has the lowest regional average of 24.3 µg/m3 but the peak recorded in the southern metro was 192.7 µg/m3, third highest among the 10 metropolitan areas — only exceeded by Jaipur (205.9 µg/m3) and Delhi-NCR (194.2 µg/m3). Mumbai-MMR’s peak was fourth highest at 186.1 µg/m3. Lucknow had a regional average of 54.9 µg/m3 and regional peak of 179.1 µg/m3. Pune had a regional average of 53.6 µg/m3 and a regional peak of 163.6 µg/m3. Ahmedabad had a regional average of 53.3 µg/m3 and regional peak of 172.6 µg/m3. Kolkata-KMA had a regional average of 38.8 µg/m3 and regional peak of 160.4 µg/m3. Bengaluru had a regional average of 35.3 µg/m3 and regional peak of 110.7 µg/m3 (lowest peak among the metropolitan areas). Hyderabad had a regional average of 32.8 µg/m3 and regional peak of 129.1 µg/m3. Says Somvanshi: “Given the data cap of 200 µg/m3 enforced by the CPCB at 15-minute granularity, it is stunning to observe that multiple stations are still logging eight-hourly averages close to 200 µg/m3 across the country. This underscores the magnitude of the pollution.” Duration of ground-level ozone pollution exceedance unhealthily long across all metropolitan areas, smaller metropolitan areas worst: Ground-level ozone exposure standard is defined in terms of one-hourly average and eight-hourly average — but this standard is breeched for much longer durations. This summer, at the stations which reported exceedance, it lasted on an average of 11.9 hours in Bengaluru which was the lowest among the 10 metropolitan areas; the highest was in Lucknow where it lasted an average of 15.7 hours. Average exceedance duration in Pune, Jaipur and Ahmedabad was 15.1 hours, 14.2 hours and 14.2 hours respectively. Average duration ranged between 12 and 14 hours for Delhi-NCR, Mumbai-MMR, Chennai, Kolkata-KMA and Hyderabad. Night-time ground-level ozone continues to persist in all metropolitan areas: Ground-level ozone should ideally become negligible in the night air, but all 10 metropolitan areas have been witnessing a rare phenomenon where ozone levels remain elevated hours after sunset. Night-time ozone has been considered when hourly concentration has exceeded the level of 100 µg/m3 between 10 PM and 2 AM at any station. Mumbai-MMR reported most instances of night-time ground-level ozone, with 171 nights of exceedance. It is followed by Delhi-NCR and Pune with 161 nights and 131 nights respectively. Hyderabad recorded exceedance on 94 nights; Ahmedabad, on 68 nights. Lucknow had 26 exceedance nights while Chennai had 24 and Bengaluru, 22. The least number of exceedances was recorded in Kolkata: 17 nights. Like day-time ground-level ozone exceedance, night-time exceedances are also recorded throughout January to July in all metropolitan areas. But unlike day-time exceedances, there is no regional variation in the seasonality of night-time exceedances as all metropolitan areas record a majority of them during summer (April-July). Ground-level ozone hotspots are located in areas with low levels of NO2 and PM2.5: The spatial distribution of ground-level ozone is the inverse of NO2 and PM2.5. This bears out the fact that while ozone is created in polluted areas with nitrogen oxide being the catalyst, it also gets mopped up in high NO2 areas as it further reacts. But the ozone that escapes to cleaner areas with less NO2 builds up faster, as unavailability of NO2 hampers its dissipation. High end and green neighborhoods are worst affected: Dr Karni Singh Shooting Range and Lodi Colony in Delhi, Navy Nagar in Mumbai, Fort William in Kolkata, Kapra in Hyderabad, BMT Layout in Bengaluru, Velachery in Chennai, Savitribai Phule University in Pune, Police Commissionerate in Jaipur, Gomti Nagar in Lucknow and Maninagar in Ahmedabad are all hotspots for ground-level ozone pollution. “This is consistent with the science that ozone drifts and gathers in areas where comparativey lesser amount of gaseous pollutants are persent to further mop it up. Thus, relatively cleaner areas including urban peripheries can have comparatively higher ozone concentration,” says Roychowdhury. Ground-level ozone has become a year-long problem: “Even though ground-level ozone exceedance is assumed to be at its worst during summer months, data from the 10 metropolitan areas analysed in our study shows that it remains a year-long problem,” says Somvanshi. The intensity and spatial spread dip during non-summer days, but a few locations continue to record exceedance throughout the year. Build-up of ground-level ozone can happen anytime during the year in the sunnier metropolitan areas of south India, but it occurs usually in small pockets during the non-summer months. For it to have a wider spatial spread, hot and sunny weather conditions are needed which are generally present in summer – especially during April-May; but there is a considerable uptick in ozone pollution after monsoon, especially during October-November. Foggy and cold conditions of January in north India conventionally inhibit formation of ground-level ozone. But the study found that ozone was exceeding at multiple stations in Delhi. Critical to act immediately Says Roychowdhury: “This finding has significant implcations for the NCAP programme that is currently focusing more on controlling PM10 or coarse dust. India must immediately refine the action strategy for combined control of particulate pollution, ozone and its precursor gases like NOx to maximise the co-benefits of the action plan. We need stringent control of precursor gases from vehicles, industry, cooking on solid fuels, open burning and other combustion sources while reducing PM2.5.” Simultaneously, the country needs to develop a robust public information and dissemination system to alert the public about ozone exceedance — wherever ozone build-up is happening.

Forbidden ozone

This year so far, Bengaluru has recorded 59 days of ground-level ozone breaching the safe limits, according to a new analysis by the Centre for Science and Environment (CSE), New Delhi. The assessment was conducted on air quality data from 14 Continuous Ambient Air Quality Monitoring Systems (CAAQMS) across the city. The results of the assessment also underline that BTM Layout is the hotspot for ground-level ozone pollution in the city. An increase in ground-level ozone above prescribed standards has been calculated as a daily maximum eighthour average crossing the standard of 100µg/m3. Ozone levels also remained elevated in the city hours after sunset. Bengaluru has recorded 22 nights with higherthan-safe ground-level ozone values. Night-time ozone has been considered when hourly concentration has exceeded the level of 100 µg/m3 between 10 pm and 2 am at any station. Consequences Experts say ground-level ozone is a highly reactive gas and has serious health consequences.

Delhi suffers from high levels of ground-level ozone, finds study

Delhi-NCR topped a list of 10 cities across the country that were found to have high concentrations of ground-level ozone (O3), according to a study released by the Centre for Science and Environment (CSE) on Tuesday. According to the study, between January 1 and July 18 — a period of 200 days — Delhi-NCR recorded 176 days of ground-level ozone exceedance. The second highest was 138 days each, in Mumbai-MMR and Pune, followed by Jaipur, at 126 days. CSE used data from official stations under the Continuous Ambient Air Quality Monitoring System (CAAQMS) of the Central Pollution Control Board. “Ground-level ozone, a highly reactive gas, has serious health consequences. Those with respiratory conditions, asthma and chronic obstructive pulmonary disease, as well as children with premature lungs and older adults, are at serious risk. This can inflame and damage airways, make lungs susceptible to infection, aggravate asthma, emphysema and chronic bronchitis, and increase the frequency of asthma attacks leading to increased hospitalisation,” Anumita Roychowdhury, executive director, research and advocacy, CSE, said. The study looked at ozone data from January 1 to July 18, with the summer period considered as April 1 to July 18. Comparative data was assessed from 2020 till 2023, covering Bengaluru, Chennai, Delhi-NCR, Greater Ahmedabad, Greater Hyderabad, Greater Jaipur, Kolkata, Greater Lucknow, Mumbai Metropolitan Region and Pune. Ground-level ozone is not directly emitted, but is produced from a complex interaction between nitrogen oxides (NOx) and volatile organic compounds (VOCs) emitted from vehicles, power plants, factories, and other combustion sources. This makes it a highly volatile gas that has one-hour and eight-hour standards, as compared to PM (particulate matter) 2.5, which has a 24-hour standard. Dangerous levels Delhi-NCR recorded excess ozone levels on 103 of 109 days this summer, followed by Jaipur, at 75 days, and Pune, at 58 days. However, based on concentration levels, Jaipur’s air was more toxic than that of Delhi-NCR. “The regional average of Jaipur for April 1 to July 15 is 81.2 µg/m3 compared to Delhi-NCR’s 73.3µg/m3 and Mumbai-MMR’s 34.8µg/m3. Chennai has the lowest regional average of 24.3µg/m3 but the peak recorded in the southern metro was 192.7µg/m3, third highest among the 10 metropolitan areas -- only exceeded by Jaipur (205.9µg/m3) and Delhi-NCR (194.2µg/m3),” the study said. “While analysing the data, it was also noted that the ozone data available on the CPCB portal never exceeds 200 microgramme per cubic metre (μg/m3) while data for the corresponding time provided by the Delhi Pollution Control Committee may show higher levels. Due to this capping of data, it is not possible to understand the nature of peaking in the city,” Avikal Somvanshi, programme manager, Urban Lab, CSE, who was also part of the study, said. According to CPCB, the one-hour standard for ozone is 180µg/m3, and the eight-hourly standard is 100µg/m3. Night ozone CSE said that although ground-level ozone should ideally become negligible in the night air, the 10 metropolitan areas have been witnessing a rare phenomenon, where ozone levels remain elevated for hours after sunset. The report said Mumbai-MMR reported most instances of night-time ground-level ozone, with 171 nights of exceedance, followed by Delhi-NCR, at 161, and Pune, at 131 nights. The least number of exceedances was recorded in Kolkata, on 17 nights. Year-on-year increase Comparing the number of exceedances this year with the same period from last year shows an increase in seven of 10 metropolitan areas, the study found. Smaller metropolitan areas had the biggest jumps, with Ahmedabad registering a 4,000% rise in number of exceedances, followed by Pune, with a 500% rise and Jaipur, with a 152% rise. “Hyderabad registered a 115% rise in the number of exceedance days; Mumbai-MMR and Bengaluru saw an 18% and 1% increase, respectively. Less than 5% change has been noted in Delhi-NCR and Lucknow. Meanwhile, Kolkata-KMA and Chennai have seen a drop in the number of exceedances by 19% and 40%, respectively,” the study said. Green areas worst hit The study found that green or high-end neighbourhoods were worst impacted, indicating that though these areas may have lesser PM 2.5, ozone remains a threat. According to the study, Dr Karni Singh Shooting Range and Lodi Colony in Delhi, Navy Nagar in Mumbai, Fort William in Kolkata, Kapra in Hyderabad, BMT Layout in Bengaluru, Velachery in Chennai, Savitribai Phule University in Pune, Police Commissionerate in Jaipur, Gomti Nagar in Lucknow and Maninagar in Ahmedabad are all hot spots of ground-level ozone pollution. “This is consistent with the science that ozone drifts and gathers in areas where comparatively lesser amount of gaseous pollutants are present to further mop it up. Thus, relatively cleaner areas, including urban peripheries, can have comparatively higher ozone concentrations,” Roychowdhury said. The spatial distribution of ozone was also found to be inverse of NO2 and PM2.5. “This bears out the fact that while ozone is created in polluted areas with nitrogen oxide being the catalyst, it also gets mopped up in high NO2 areas as it further reacts. But the ozone that escapes to cleaner areas with less NO2 builds up faster, as unavailability of NO2 hampers its dissipation,” the study said.

Delhi suffers from high levels of ground-level ozone, finds study

Delhi-NCR topped a list of 10 cities across the country that were found to have high concentrations of ground-level ozone (O3), according to a study released by the Centre for Science and Environment (CSE) on Tuesday. According to the study, between January 1 and July 18 — a period of 200 days — Delhi-NCR recorded 176 days of ground-level ozone exceedance. The second highest was 138 days each, in Mumbai-MMR and Pune, followed by Jaipur, at 126 days. CSE used data from official stations under the Continuous Ambient Air Quality Monitoring System (CAAQMS) of the Central Pollution Control Board. “Ground-level ozone, a highly reactive gas, has serious health consequences. Those with respiratory conditions, asthma and chronic obstructive pulmonary disease, as well as children with premature lungs and older adults, are at serious risk. This can inflame and damage airways, make lungs susceptible to infection, aggravate asthma, emphysema and chronic bronchitis, and increase the frequency of asthma attacks leading to increased hospitalisation,” Anumita Roychowdhury, executive director, research and advocacy, CSE, said. The study looked at ozone data from January 1 to July 18, with the summer period considered as April 1 to July 18. Comparative data was assessed from 2020 till 2023, covering Bengaluru, Chennai, Delhi-NCR, Greater Ahmedabad, Greater Hyderabad, Greater Jaipur, Kolkata, Greater Lucknow, Mumbai Metropolitan Region and Pune. Ground-level ozone is not directly emitted, but is produced from a complex interaction between nitrogen oxides (NOx) and volatile organic compounds (VOCs) emitted from vehicles, power plants, factories, and other combustion sources. This makes it a highly volatile gas that has one-hour and eight-hour standards, as compared to PM (particulate matter) 2.5, which has a 24-hour standard. Dangerous levels Delhi-NCR recorded excess ozone levels on 103 of 109 days this summer, followed by Jaipur, at 75 days, and Pune, at 58 days. However, based on concentration levels, Jaipur’s air was more toxic than that of Delhi-NCR. “The regional average of Jaipur for April 1 to July 15 is 81.2 µg/m3 compared to Delhi-NCR’s 73.3µg/m3 and Mumbai-MMR’s 34.8µg/m3. Chennai has the lowest regional average of 24.3µg/m3 but the peak recorded in the southern metro was 192.7µg/m3, third highest among the 10 metropolitan areas -- only exceeded by Jaipur (205.9µg/m3) and Delhi-NCR (194.2µg/m3),” the study said. “While analysing the data, it was also noted that the ozone data available on the CPCB portal never exceeds 200 microgramme per cubic metre (μg/m3) while data for the corresponding time provided by the Delhi Pollution Control Committee may show higher levels. Due to this capping of data, it is not possible to understand the nature of peaking in the city,” Avikal Somvanshi, programme manager, Urban Lab, CSE, who was also part of the study, said.

High concentrations of ground-level ozone in India’s major metropolitan areas, says new CSE study

A new nation-wide analysis by Centre for Science and Environment (CSE) says that in the summer of 2024, the levels of ground-level ozone in the air went up in the 10 major metropolitan areas of Ind These areas and cities include Bengaluru Metropolitan Area (Karnataka), Chennai Metropolitan Area (Tamil Nadu), Delhi-NCR, Greater Ahmedabad (Gujarat), Greater Hyderabad (Telangana), Greater Jaipur (Rajasthan), Kolkata Metropolitan Area (West Bengal), Greater Lucknow (Uttar Pradesh), Mumbai Metropolitan Region (Maharashtra) and Pune Metropolitan Region (Maharashtra). Says Anumita Roychowdhury, executive director, research and advocacy, CSE: “Ground-level ozone, a highly reactive gas, has serious health consequences. Those with respiratory conditions, asthma and chronic obstructive pulmonary disease – as well as children with premature lungs and older adults — are at serious risk. This can inflame and damage airways, make lungs susceptible to infection, aggravate asthma, emphysema, and chronic bronchitis and increase the frequency of asthma attacks leading to increased hospitalisation.” The 2020 State of Global Air report states that age-standardised rates of death attributable to ground-level ozone is among the highest in India. The seasonal eight-hour daily maximum concentrations have recorded one of the highest increases in India between 2010 and 2017 – about 17 per cent. Ozone needs special attention — ground-level ozone is not directly emitted from any source. It is produced from complex interaction between nitrogen oxides (NOx) and volatile organic compounds (VOCs) that are emitted from vehicles, power plants, factories, and other combustion sources and undergo cyclic reactions in the presence of sunlight to generate ground-level ozone. VOCs can also be emitted from natural sources, such as plants. Roychowdhury points out that as the National Clean Air Programme (NCAP) gears up for its second phase, “its reform agenda has to address the multi-pollutant crisis and the combined threat from PM2.5, ozone, nitrogen oxides and other gases. Global experience shows that there is usually a trade-off — as particulate pollution gets reduced, the problem of NOx and ground-level ozone increases. This requires significant tightening of the regulatory benchmark for ozone to address the toxic emisisons from industry, vehicles, households and open burning”. “Moreover, ozone not only builds up in metropolitan areas but also drifts long distances to form a regional pollutant that makes both local and regional action necessary,” she adds. According to Avikal Somvanshi, programme manager, Urban Lab, CSE, who has led the CSE study, “in 2024, we have found that the geographical spread of the problem is much wider than what we had seen in the lockdown summer of 2020 in most metropolitan areas. This time’s toxic build-up has lasted longer in locations affected by the problem. Even the smaller metropolitan areas have witnessed rapid increase. In metropolitan areas in the south and western coastal belt, the problem is not limited only to the summer months.” Adds Somvanshi: “Inadequate monitoring, limited data and inappropriate methods of trend analysis have weakened the understanding of this growing public health hazard. The complex chemistry of ground-level ozone makes it a difficult pollutant to track and mitigate. Due to its toxic nature, ozone’s national ambient air quality standard has been set for only short-term exposures (one-hour and eight-hour averages), and compliance is measured by the number of days that exceed the standards. This requires early action.” The investigation methodology This assessment has traced trends during summer (April 1-July 18). The data covered is from 2020 to 2024. The analysis is based on publicly available granular real time data (15-minute averages) from the Central Pollution Control Board’s (CPCB) official online portal, the Central Control Room for Air Quality Management. The data has been captured from official stations under the Continuous Ambient Air Quality Monitoring System (CAAQMS) spread across 10 metropolitan regions. The station break-up is as follows: Delhi-NCR (58 stations), Mumbai Metropolitan Region (48), Kolkata Metropolitan Area (10), Greater Hyderabad (14), Bengaluru Metropolitan Area (14), Chennai Metropolitan Area (nine), Pune Metropolitan Region (15), Greater Ahmedabad (10), Greater Lucknow (seven) and Greater Jaipur (six).

द‍िल्‍ली के 3 करोड़ लोगों के ल‍िए बुरी खबर... सेंटर फॉर साइंस एंड एनवायरनमेंट की ये र‍िपोर्ट जरूर पढ़नी चाह‍िए

दिल्ली-एनसीआर के लोगों के लिए एक बुरी खबर है. सेंटर फॉर साइंस और एनवायर्मेंट (CSE) ने एक स्टडी की है, जिससे यहां रहने वाली करीब तीन करोड़ लोगों की सेहत पर आने वाले दिनों ने खतरा पैदा हो सकता है. CSE के विश्लेषण के अनुसार इस साल गर्मियों के दौरान भारत के 10 मेट्रो शहरों ग्राउंड-लेवल ओजोन (एक तरह की खतरनाक गैस) की मात्रा बढ़ गई, जिसमें दिल्ली सबसे प्रभावित शहर था. इस अध्ययन की अवधि के दौरान, दिल्ली-एनसीआर ने 176 दिन ओजोन मानक को पार करने का रिकॉर्ड बनाया, जबकि मुंबई और पुणे में यह आंकड़ा 138 दिन का रहा. दिल्ली-एनसीआर की समस्या CSE के अनुसार गर्मियों में दिल्ली-एनसीआर में ओजोन मानक अक्सर हर दिन पार हो जाता है. इस साल दिल्ली-एनसीआर के मुख्य क्षेत्रों में 17.6 स्टेशनों पर मानक से अधिक ओजोन पाया गया, जो पिछले पांच वर्षों में सबसे अधिक है. पिछले गर्मियों में औसतन 9.4 स्टेशनों पर मानक पार होता था, जबकि 2020 की गर्मियों में यह संख्या 14.6 थी. रात के समय भी बढ़ी ओजोन की मात्रा रात के समय ओजोन की मात्रा सामान्यतः नगण्य होनी चाहिए, लेकिन इस साल 10 मेट्रो में रात के समय भी ओजोन की उच्च मात्रा देखने को मिली. अध्ययन ने रात 10 बजे से 2 बजे तक किसी भी स्टेशन पर 100 माइक्रोग्राम प्रति घन मीटर से अधिक ओजोन को अधिक माना. मुंबई में सबसे अधिक रात के समय ओजोन की घटनाएं दर्ज की गईं. मुंबई में 171 रातों में, दिल्ली-एनसीआर में 161 रातें और पुणे में 131 रातों में ओजोन बढ़ा मिला. स्वास्थ्य पर प्रभाव ग्राउंड-लेवल ओजोन एक अत्यधिक प्रतिक्रियाशील गैस है, जिसके गंभीर स्वास्थ्य परिणाम हो सकते हैं. इससे सांस की समस्या, अस्थमा और क्रोनिक ऑब्सट्रक्टिव पल्मोनरी डिजीज (COPD) हो सकता है. छोटे बच्चे जिनकी फेफड़े पूरी तरह से विकसित नहीं हैं और बुजुर्गों को गंभीर जोखिम हो सकता है. अस्थमा, एम्फीजीमा और क्रोनिक ब्रोंकाइटिस को बढ़ा सकती है और अस्थमा के हमले बढ़ा सकती है. इस साल दिल्ली-एनसीआर में ओजोन का विस्तार और अवधि दोनों ही बढ़ गए हैं. गर्मियों में, जिन स्टेशनों पर मानक पार हुआ, वहां ओजोन की उच्च मात्रा औसतन 13.9 घंटे तक रही, जो 2020 की महामारी की गर्मियों के बाद सबसे अधिक है. हरित और ऊंचाई वाले क्षेत्रों में भी प्रभाव मेट्रो क्षेत्रों के ऊंचाई वाले और हरित इलाकों को भी इस समस्या का सामना करना पड़ा. स्टडी में कहा गया है कि यह विज्ञान के साथ संगत है कि ओजोन उन क्षेत्रों में जमा होता है जहां गैसीय प्रदूषकों की मात्रा कम होती है. इसलिए अपेक्षाकृत साफ क्षेत्रों, जिसमें शहरी बाहरी इलाके भी शामिल हैं, में ओजोन की मात्रा अधिक हो सकती है. 2020 की ग्लोबल एयर रिपोर्ट के अनुसार, ग्राउंड-लेवल ओजोन के कारण भारत में सबसे अधिक लोगों की मौत होती. CSE ने सुझाव दिया है कि देश को एक मजबूत सार्वजनिक सूचना और प्रसार प्रणाली विकसित करनी चाहिए ताकि जहां भी ओज़ोन का जमाव हो, वहां जनता को सतर्क किया जा सके.द

इस वर्ष गर्मी में 10 प्रमुख शहरों क्षेत्रों में ओजोन बढ़ा, दिल्ली सबसे अधिक प्रभावित

राज्य ब्यूरो, नई दिल्ली। राष्ट्रीय राजधानी में इस बार लोगों ने खतरनाक गर्मी का अनुभव किया। मौसम के इस अप्रत्याशित बदले पैटर्न पर सेंटर फॉर साइंस एंड एनवायरनमेंट (सीएसई) द्वारा गहन अध्ययन किया गया। इस नए अघ्ययन में कहा गया है कि 2024 की गर्मियों में, भारत के 10 प्रमुख महानगरीय क्षेत्रों में ओजोन का स्तर बढ़ गया। इनमें राष्ट्रीय राजधानी को बुरी तरह प्रभावित पाया गया। जहां यह अध्ययन किया गया है उनमें बेंगलुरु मेट्रोपॉलिटन एरिया (कर्नाटक), चेन्नई मेट्रोपॉलिटन एरिया (तमिलनाडु), दिल्ली-एनसीआर, ग्रेटर अहमदाबाद (गुजरात), ग्रेटर हैदराबाद (तेलंगाना), ग्रेटर जयपुर (राजस्थान), कोलकाता मेट्रोपॉलिटन एरिया (पश्चिम बंगाल), ग्रेटर लखनऊ (उत्तर प्रदेश), मुंबई मेट्रोपॉलिटन क्षेत्र (महाराष्ट्र) और पुणे मेट्रोपॉलिटन क्षेत्र (महाराष्ट्र) शामिल हैं। सीएसई के शहरी प्रयोगशाला के कार्यक्रम प्रबंधक अविकल सोमवंशी बताते हैं कि इस अध्ययन के लिए एक अप्रैल से 18 जुलाई तक 2020 से 2024 तक के आंकड़े लिए गए हैं। कौन से शहर में ओजोन की अधिकता सभी 10 महानगरीय क्षेत्रों में जमीनी स्तर पर ओजोन की अधिकता सामने आई है। इनमें दिल्ली सबसे अधिक प्रभावित है। इस वर्ष अब तक दिल्ली-एनसीआर में 176 दिनों की अधिकता दर्ज की गई है। मुंबई और पुणे 138 दिनों की अधिकता के साथ दूसरे स्थान पर हैं। जयपुर में 126 दिनों, हैदराबाद 86 दिन, कोलकाता 63 दिन, बेंगलुरु 59 दिन, लखनऊ 49 दिन और अहमदाबाद में 41 दिन की अधिकता देखी गई है। सबसे कम संख्या में अधिकता चेन्नई में दर्ज की गई मात्र नौ दिन। 1 अप्रैल से 15 जुलाई तक जयपुर में ओजोन का क्षेत्रीय औसत 81.2 माइक्रोग्राम प्रति घन मीटर है, जबकि एनसीआर का 73.3 माइक्रोग्राम प्रति घन मीटर और मुंबई का 34.8 माइक्रोग्राम प्रति घन मीटर है। चेन्नई का क्षेत्रीय औसत सबसे कम 24.3 माइक्रोग्राम प्रति घन मीटर है, लेकिन दक्षिणी मेट्रो में शिखर 192.7 माइक्रोग्राम प्रति घन मीटर दर्ज किया गया, जो 10 महानगरीय क्षेत्रों में तीसरा सबसे अधिक है। दिल्ली में डॉ. कर्णी सिंह शूटिंग रेंज और लोदी कॉलोनी, मुंबई में नेवी नगर, कोलकाता में फोर्ट विलियम, हैदराबाद में कपरा, बेंगलुरु में बीएमटी लेआउट, चेन्नई में वेलाचेरी, पुणे में सावित्रीबाई फुले विश्वविद्यालय, पुलिस जयपुर में कमिश्नरेट, लखनऊ में गोमती नगर और अहमदाबाद में मणिनगर सभी जमीनी स्तर पर ओजोन प्रदूषण के हॉटस्पॉट हैं। सीएसई की रिसर्च व एडवोकेसी की कार्यकारी निदेशक अनुमिता राय चौधरी बताती हैं कि 2020 स्टेट ऑफ ग्लोबल एयर रिपोर्ट में कहा गया है कि भारत में जमीनी स्तर पर ओजोन के कारण होने वाली मृत्यु की आयु-मानकीकृत दरें सबसे अधिक हैं। मौसमी आठ घंटे की दैनिक अधिकतम सांद्रता ने 2010 और 2017 के बीच भारत में सबसे अधिक लगभग 17 प्रतिशत वृद्धि दर्ज की है।

Dehli: दिल्ली में जमीनी स्तर पर ओजोन का स्तर बहुत अधिक

मंगलवार को सेंटर फॉर साइंस एंड एनवायरनमेंट (CSE) द्वारा जारी एक अध्ययन के अनुसार, दिल्ली-एनसीआर देश भर के उन 10 शहरों की सूची में सबसे ऊपर है, जिनमें ग्राउंड-लेवल ओजोन (O3) की उच्च सांद्रता पाई गई है।मंगलवार को सेंटर फॉर साइंस एंड एनवायरनमेंट (CSE) द्वारा जारी एक अध्ययन के अनुसार, दिल्ली-एनसीआर देश भर के उन 10 शहरों की सूची में सबसे ऊपर है, जिनमें ग्राउंड-लेवल ओजोन (O3) की उच्च सांद्रता पाई गई है। अध्ययन में 1 जनवरी से 18 जुलाई तक के ओजोन डेटा को देखा गया, जिसमें गर्मियों की अवधि 1 अप्रैल से 18 जुलाई मानी गई। तुलनात्मक डेटा का मूल्यांकन 2020 से 2023 तक किया गया, जिसमें बेंगलुरु, चेन्नई, दिल्ली-एनसीआर, ग्रेटर अहमदाबाद, ग्रेटर हैदराबाद, ग्रेटर जयपुर, कोलकाता, ग्रेटर लखनऊ Greater Lucknow, मुंबई मेट्रोपॉलिटन क्षेत्र और पुणे शामिल थे। ग्राउंड-लेवल ओजोन सीधे उत्सर्जित नहीं होता है, बल्कि वाहनों, बिजली संयंत्रों, कारखानों और अन्य दहन स्रोतों से उत्सर्जित नाइट्रोजन ऑक्साइड (NOx) और वाष्पशील कार्बनिक यौगिकों (VOCs) के बीच एक जटिल बातचीत से उत्पन्न होता है। यह इसे अत्यधिक अस्थिर गैस बनाता है, जिसका एक घंटे और आठ घंटे का मानक है, जबकि पीएम (पार्टिकुलेट मैटर) 2.5 का मानक 24 घंटे का है। खतरनाक स्तर इस गर्मी में दिल्ली-एनसीआर में 109 दिनों में से 103 दिनों में ओजोन का स्तर अत्यधिक दर्ज किया गया, इसके बाद जयपुर में 75 दिन और पुणे में 58 दिन अत्यधिक ओजोन स्तर दर्ज किया गया। हालांकि, सांद्रता के स्तर के आधार पर, जयपुर की हवा दिल्ली-एनसीआर की तुलना में अधिक जहरीली थी। "1 अप्रैल से 15 जुलाई तक जयपुर का क्षेत्रीय औसत 81.2 µg/m3 है, जबकि दिल्ली-एनसीआर का 73.3 µg/m3 और मुंबई-एमएमआर का 34.8 µg/m3 है। चेन्नई में सबसे कम क्षेत्रीय औसत 24.3µg/m3 है, लेकिन दक्षिणी महानगर में दर्ज किया गया शिखर 192.7µg/m3 था, जो 10 महानगरीय क्षेत्रों में तीसरा सबसे अधिक है - केवल जयपुर (205.9µg/m3) और दिल्ली-एनसीआर (194.2µg/m3) ही इससे आगे हैं,” अध्ययन में कहा गया है। आंकड़ों का विश्लेषण करते समय, यह भी पाया गया कि सीपीसीबी पोर्टल पर उपलब्ध ओजोन डेटा कभी भी 200 माइक्रोग्राम प्रति क्यूबिक मीटर (μg/m3) से अधिक नहीं होता है, जबकि दिल्ली प्रदूषण नियंत्रण समिति द्वारा प्रदान किए गए इसी समय के डेटा में उच्च स्तर दिखाई दे सकते हैं। डेटा की इस सीमा के कारण, शहर में चरम की प्रकृति को समझना संभव नहीं है,” सीएसई के शहरी प्रयोगशाला के कार्यक्रम प्रबंधक अविकल सोमवंशी, जो अध्ययन का हिस्सा भी थे, ने कहा।सीपीसीबी के अनुसार, ओजोन के लिए एक घंटे का मानक 180µg/m3 है, और आठ घंटे का मानक 100µg/m3 है।

Ozone build-up: Delhi-NCR and other metropolitan areas of India confront new air quality crisis

Each year during winter, Delhi-NCR hits the headl that surpasses all permissible limits. However, the concern. According to an analysis by the Centre for (CSE), ground-level ozone increased in 10 metrop summer, with Delhi being the most affected, as rep further highlighted that Delhi-NCR recorded 176 d study period, followed by Mumbai and Pune with 1 According to CSE, it is common for ground-level oz during summer in some locations in Delhi-NCR. However, this year, the number of station across core NCR reached 17.6, the highest in the last five years. Previously, only 9.4 station on average. This number gradually increased, reaching 14.6 stations with exceeded limits The report notes that ideally, ground-level ozone should be negligible at night. However, it a surge in ozone levels after sunset in all 10 metropolitan areas Why is ground-level ozone considered dangerous? According to the report, ground-level ozone is a highly reactive gas that can create serious respiratory conditions, asthma, chronic obstructive pulmonary disease, children with de adults are at serious risk. The gas can inflame and damage airways, make lungs susceptibl asthma, emphysema, and chronic bronchitis, and increase the frequency of asthma attack Roychowdhury, Executive Director of Research and Advocacy at CSE. Another concern is that even in Delhi’s green neighborhoods, high levels of ground-level o areas like Dr Karni Singh Shooting Range and Lodhi Colony. “This is consistent with the s gathers in areas with relatively lower amounts of gaseous pollutants. Thus, relatively clea peripheries, can have comparatively higher ozone concentrations,” added Roychowdhury Avikal Somvanshi, Programme Manager at Urban Lab, CSE, who led the study, said, “Even exceedance is typically worse during summer months, data from the 10 metropolitan area that it is a year-round problem.” 8/7/24, 3:30 PM Ozone build-up: Delhi-NCR and other metropolitan areas of India confront new air quality crisis - CSE asserted that the country should develop a robust public information and dissemin wherever ozone build-up occurs

An invisible threat: Summary report of ground-level ozone pollution analysis of 10 major metropolitan areas of India

The summer of 2024 has witnessed widespread ground-level ozone exceedance making the air more toxic across 10 major metropolitan areas of India. This time the geographical spread of the problem is much wider than the lockdown summer of 2020 in most metropolitan areas. The phase of the toxic built up has lasted longer in locations affected by the problem. Even the smaller metropolitan areas have witnessed rapid increase. In metropolitan areas in the south and western coastal belt the problem is not limited only to summer months.

Surge in Ground-Level Ozone Levels in India’s Major Cities: CSE Report

A nationwide analysis conducted by the Centre for Science and Environment (CSE) reveals a significant rise in ground-level ozone concentrations across ten major metropolitan areas in India during the summer of 2024. The affected cities include Bengaluru, Chennai, Delhi-NCR, Greater Ahmedabad, Greater Hyderabad, Greater Jaipur, Kolkata, Greater Lucknow, Mumbai, and Pune. Anumita Roychowdhury, Executive Director of Research and Advocacy at CSE, underscores the health risks associated with ground-level ozone. "This highly reactive gas poses serious health hazards, particularly for individuals with respiratory conditions such as asthma and chronic obstructive pulmonary disease, as well as children and the elderly," Roychowdhury explains. The gas inflames airways, increases susceptibility to infections, and can exacerbate chronic respiratory conditions, leading to more frequent hospitalizations. The 2020 State of Global Air report highlights that India experiences some of the highest age-standardized rates of death attributable to ground-level ozone. Between 2010 and 2017, the country saw a 17% increase in the seasonal eight-hour daily maximum concentrations of this pollutant. Ground-level ozone is not directly emitted but forms through complex interactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. These pollutants originate from vehicles, power plants, factories, and other combustion sources. VOCs can also be emitted naturally from plants. As the National Clean Air Programme (NCAP) approaches its second phase, Roychowdhury emphasizes the need for a comprehensive approach to tackle the multi-pollutant crisis, which includes ground-level ozone. “There is often a trade-off where reducing particulate pollution can lead to increased NOx and ground-level ozone. We need stricter regulatory benchmarks for ozone and better controls on emissions from industries, vehicles, households, and open burning,” she says. Avikal Somvanshi, Programme Manager at CSE, highlights the broader geographic spread of ozone pollution in 2024 compared to the lockdown summer of 2020. This year’s data shows a prolonged toxic buildup in affected areas, including smaller metropolitan regions. The issue is now observed to persist beyond summer in some locations. The study, which covers data from April 1 to July 18, 2024, uses real-time data from the Central Pollution Control Board’s (CPCB) online portal. The analysis reveals that ground-level ozone exceedances were reported across all ten metropolitan areas, with Delhi-NCR experiencing the highest number of exceedance days at 176. Mumbai and Pune follow with 138 days each. The report notes a dramatic increase in exceedances in smaller metropolitan areas, with Ahmedabad showing a 4,000% rise, followed by Pune at 500% and Jaipur at 152%. This is contrasted with a decrease in exceedances in Kolkata and Chennai. The intensity of ground-level ozone pollution remains high across all metropolitan areas, with Jaipur recording the highest regional average and peak levels. Despite the highest number of exceedance days being in Delhi-NCR and Mumbai, Jaipur’s air has been found to be the most toxic in terms of regional averages and peaks. The study also points out that ground-level ozone levels remain elevated even at night in all metropolitan areas, with Mumbai reporting the most instances of night-time exceedance. Sharanjeet Kaur, Programme Officer at CSE, calls for improvements in monitoring and trend analysis methods. The current compliance standards, which allow exceedances on a limited number of days, do not adequately address the local impacts of ozone pollution. The report suggests that a city-wide average is insufficient to capture the severity of ground-level ozone pollution and its health implications. As ground-level ozone continues to pose a year-round challenge, particularly in sunny and less polluted areas, Roychowdhury stresses the need for an immediate and robust response. “The NCAP must refine its strategy to address not only PM10 but also ozone and its precursors. Effective action requires stringent controls on emissions and improved public awareness systems,” she concludes. This analysis underscores the urgent need for comprehensive policies and public health interventions to mitigate the growing threat of ground-level ozone pollution in India’s urban centers.