Gurgaon: The city witnessed a significant rise in nitrous oxide (NO2), surpassing acceptable limits at numerous areas between Oct 26 and Nov 8. While authorities focus on controlling PM2.5 and PM10 emissions, NO2 concentrations have received limited attention, despite reaching nearly four times the global safety standards, as indicated by pollution monitoring stations across the city.
Data from the Sector 51 monitoring station showed NO2 levels of 102 µg/m³ on Oct 27, 87 µg/m³ on Oct 28, 105 µg/m³ on Nov 1, 78 µg/m³ on Nov 3 and 87 µg/m³ on Nov 7. Gwalpahari station recorded 107 µg/m³ on Nov 2 and 101 µg/m³ on Nov 8. These figures significantly exceed both CPCB's annual limit of 40 µg/m³ and WHO's safe limit of 25 µg/m³.
Extended exposure to high NO2 levels can result in chronic lung disease, diminished sense of smell, and damage to vegetation.
Experts identified vehicles as the primary source of NO2 in the city. Sector 51 recorded the highest pollution levels, including AQI, PM2.5, PM10, and NO2, due to its dense housing, traffic congestion, urban settlements, poor road conditions and construction activities. The main NO2 contributors include road transport, coal-powered energy generation, and industrial activities.
Shubhansh Tiwari, a research associate at Centre for Science and Environment (CSE), said, "The elevated NO2 levels in the city are predominantly due to vehicular emissions. Old vehicles and traffic congestion are the key sources of NO2 here. It has been observed that during winter, the air quality oscillates between "very poor" and "severe" as condensation of fine particulate matter in the lower layer of the atmosphere."
"We have also given NOC to a private firm in Manesar to scrap old vehicles. This aims to remove polluting vehicles from the city roads," HSPCB regional officer Vijay Chaudhary.
"NO₂ is a harmful gaseous air pollutant generated when fossil fuels like coal, oil, natural gas or diesel are burnt at high temperatures. Along with PM2.5, NO₂ is associated with various adverse health effects and is a major pollutant in traffic emissions. Each year, particularly during winter, air quality deteriorates due to these pollutants, affecting people in both urban and rural areas. According to the report of Indian Agricultural Research Institute (IARI), the number of farm fires rose from 60 on Oct 30 to 605 on Oct 31. Also, the report noted that NO2 levels were higher on Diwali night this year compared to the previous year. For the past three years, NO2 levels have been elevated on Diwali night and the nights leading up to it, pointing to increased congestion and heavy traffic conditions in the city as the festival approaches," Dr Manish Bansal from Medanta said.
"Prolonged exposure to elevated levels of NO₂ can lead to numerous health issues, including chronic lung disease, decreased lung function, a higher risk of respiratory infections and asthma. It is also linked to cardiovascular problems like ischemic heart disease, stroke, acute heart failure, and inflammation. Research shows association between NO₂ exposure and neurological issues, and it may also contribute to kidney problems. Immediate symptoms include coughing, fatigue, nausea, headache, abdominal pain, and difficulty breathing," Dr Bansal added.