The Crossbill News Desk
Nitrogen dioxide levels in Delhi have surged to alarming highs, touching nearly three times the national safe limit over the past week, according to Central Pollution Control Board (CPCB) data analysed by the think tank Envirocatalysts and reported by Hindustan Times.
The findings highlight that vehicular emissions remain the city’s dominant source of this toxic gas, which is closely linked to respiratory ailments.
The analysis revealed that the hourly concentration of nitrogen dioxide (NO₂) peaked at 240 µg/m³ at the IGI Airport (T3) monitoring station, operated by the India Meteorological Department. This concentration is triple the CPCB’s safe standard of 80 µg/m³ and almost ten times the World Health Organisation’s limit of 25 µg/m³. Several other key locations in the Capital mirrored the trend, recording elevated levels through the same period.
Among these, ITO — one of Delhi’s busiest traffic intersections — reported an hourly average of 221 µg/m³, while Delhi University’s North Campus recorded 210 µg/m³. Other hotspots included Lodhi Road (181 µg/m³), Mundka (178 µg/m³) and JLN Stadium, all showing concentrations far above permissible levels.
Health experts warn that such elevated NO₂ levels can worsen asthma and other respiratory illnesses. Short-term exposure can lead to wheezing, coughing and breathing difficulties.
Envirocatalysts founder and lead analyst Sunil Dahiya explained that ITO consistently registers high NO₂ levels due to its proximity to heavy traffic.
“The station is likely to capture a significant portion of vehicular emissions, which is what people on the roadside are also inhaling,” he told the newspaper. He added that high emissions at the airport stem from a mix of aircraft and vehicular exhaust.
Experts quoted in Hindustan Times attributed Delhi’s high NO₂ concentrations to vehicular exhaust, biomass burning and industrial activity, with traffic congestion emerging as the leading factor. They estimated that vehicular emissions alone contribute as much as 81% of the Capital’s total nitrogen dioxide output.
Dahiya further observed that during the winter months, public and media attention generally focuses on particulate matter, but gases such as nitrogen dioxide also tend to spike sharply when weather conditions trap pollutants.
“At intersections or near industrial areas, if winds are stagnant and temperatures remain high, hourly peaks can rise significantly,” he said.
Echoing this, IIT Delhi professor Mukesh Khare pointed out that while vehicles are the main source, meteorological conditions play a crucial role.
“In summer, better ventilation and dispersion keep levels lower. But in winter, poor wind movement and reduced sunlight lead to greater accumulation,” he told the paper.
He added that nitrogen dioxide, primarily released from the burning of petrol and other fossil fuels, is a key indicator of traffic congestion. “Aircraft also release substantial quantities,” he noted.
Data from the CPCB revealed that several stations recorded prolonged periods above the national limit. Since November 1, the IGI Airport station logged 132 hours of exceedance, followed by 128 hours at North Campus, 118 at Najafgarh, 93 at Mundka and 81 at Lodhi Road. At Okhla Phase-II, NO₂ levels stayed above 80 µg/m³ for 75 hours, while Anand Vihar recorded 71 hours of exceedance.
However, the report also drew attention to significant gaps in Delhi’s air quality monitoring. Of the 155 hours monitored since November 1, Lodhi Road had 52 hours of missing data, Sonia Vihar 28 hours and Patparganj 13 hours. Among the 39 active monitoring stations in the city, 23 had complete data while the remaining showed at least one hour of missing readings.
A separate analysis by Hindustan Times on November 5 also highlighted missing data and inconsistencies in the algorithms used to compute Delhi’s average Air Quality Index, indicating that the actual air pollution levels could be worse than officially reported.
The findings highlight that vehicular emissions remain the city’s dominant source of this toxic gas, which is closely linked to respiratory ailments.
The analysis revealed that the hourly concentration of nitrogen dioxide (NO₂) peaked at 240 µg/m³ at the IGI Airport (T3) monitoring station, operated by the India Meteorological Department. This concentration is triple the CPCB’s safe standard of 80 µg/m³ and almost ten times the World Health Organisation’s limit of 25 µg/m³. Several other key locations in the Capital mirrored the trend, recording elevated levels through the same period.
Among these, ITO — one of Delhi’s busiest traffic intersections — reported an hourly average of 221 µg/m³, while Delhi University’s North Campus recorded 210 µg/m³. Other hotspots included Lodhi Road (181 µg/m³), Mundka (178 µg/m³) and JLN Stadium, all showing concentrations far above permissible levels.
Health experts warn that such elevated NO₂ levels can worsen asthma and other respiratory illnesses. Short-term exposure can lead to wheezing, coughing and breathing difficulties.
Envirocatalysts founder and lead analyst Sunil Dahiya explained that ITO consistently registers high NO₂ levels due to its proximity to heavy traffic.
“The station is likely to capture a significant portion of vehicular emissions, which is what people on the roadside are also inhaling,” he told the newspaper. He added that high emissions at the airport stem from a mix of aircraft and vehicular exhaust.
Experts quoted in Hindustan Times attributed Delhi’s high NO₂ concentrations to vehicular exhaust, biomass burning and industrial activity, with traffic congestion emerging as the leading factor. They estimated that vehicular emissions alone contribute as much as 81% of the Capital’s total nitrogen dioxide output.
Dahiya further observed that during the winter months, public and media attention generally focuses on particulate matter, but gases such as nitrogen dioxide also tend to spike sharply when weather conditions trap pollutants.
“At intersections or near industrial areas, if winds are stagnant and temperatures remain high, hourly peaks can rise significantly,” he said.
Echoing this, IIT Delhi professor Mukesh Khare pointed out that while vehicles are the main source, meteorological conditions play a crucial role.
“In summer, better ventilation and dispersion keep levels lower. But in winter, poor wind movement and reduced sunlight lead to greater accumulation,” he told the paper.
He added that nitrogen dioxide, primarily released from the burning of petrol and other fossil fuels, is a key indicator of traffic congestion. “Aircraft also release substantial quantities,” he noted.
Data from the CPCB revealed that several stations recorded prolonged periods above the national limit. Since November 1, the IGI Airport station logged 132 hours of exceedance, followed by 128 hours at North Campus, 118 at Najafgarh, 93 at Mundka and 81 at Lodhi Road. At Okhla Phase-II, NO₂ levels stayed above 80 µg/m³ for 75 hours, while Anand Vihar recorded 71 hours of exceedance.
However, the report also drew attention to significant gaps in Delhi’s air quality monitoring. Of the 155 hours monitored since November 1, Lodhi Road had 52 hours of missing data, Sonia Vihar 28 hours and Patparganj 13 hours. Among the 39 active monitoring stations in the city, 23 had complete data while the remaining showed at least one hour of missing readings.
A separate analysis by Hindustan Times on November 5 also highlighted missing data and inconsistencies in the algorithms used to compute Delhi’s average Air Quality Index, indicating that the actual air pollution levels could be worse than officially reported.
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