Since the start of the week, a dense smog has settled over Gurgaon, echoing the thick haze engulfing Delhi, Noida, and other parts of the National Capital Region (NCR). While Delhi’s AQI hovers around 345 (very poor) and Noida registers 318 (very poor), Gurgaon’s official reading shows a comparatively lower 221 (poor). Yet for residents stepping outside, the difference is barely noticeable, the air remains equally stifling, dusty, and hazardous.
Since Diwali, this pattern has been puzzling. Gurgaon has reported only two very poor AQI days, alongside 16 poor days and three moderate days. While wind direction and hyperlocal meteorology can explain short-term variations in air quality, a consistent discrepancy over weeks warrants closer scrutiny of the data, and, crucially, the monitoring stations themselves.
How Faulty Placement of Air Monitoring Stations Skews Gurgaon's Pollution Data
A field inspection on Monday revealed that all five Continuous Air Monitoring Stations (CAMS) in Gurgaon, Vikas Sadan, Sector 51, Teri Gram, Gwalpahari, and Manesar, are poorly positioned. Most are located near thick vegetation or walls, violating Central Pollution Control Board (CPCB) guidelines, which mandate monitors be installed 20-30 metres from trees and 50 metres away from major structures in open, well-ventilated spaces.
The placement issue is compounded by inconsistent pollutant recording. Several stations failed to consistently track PM2.5 and sulphur dioxide (SO2), the very pollutants most responsible for NCR’s toxic air. Gwalpahari and Teri Gram, in particular, have recorded incomplete indices over multiple days, artificially improving Gurgaon's average AQI.
Adding to the opacity, LED display boards at all five stations have been non-functional for weeks, leaving residents without real-time air quality information.
Vegetation Around Monitoring Stations Masks True Air Pollution Levels
Over time, lush greenery within government and institutional campuses has grown around these monitoring stations. While greenery is generally beneficial, in this case, it has inadvertently trapped air and absorbed pollutants before they reach the sensors.
An official explained: "Vegetation grew, but the monitors' locations stayed fixed. The ambient air at the stations is very different from the road-level air that residents breathe."
This means that the data from these stations does not accurately reflect the air quality that commuters, street vendors, and residents experience daily.
Missing Data Further Distorts Gurgaon's AQI Scores
CPCB real-time data analysis shows that Gwalpahari station failed to record PM2.5 levels for several hours on multiple days this month. Since AQI averages are calculated from available readings, missing PM2.5 data, NCR’s most harmful pollutant, artificially improves Gurgaon's AQI scores.
Similarly, Teri Gram station failed to record SO2 data for extended periods. This gaseous pollutant is critical for accurate AQI calculation, and its omission means that Gurgaon's reported air quality appears better than it actually is.
Shubhansh Tiwari, a research associate at the Centre for Science and Environment, said: "The stations are recording partial data and AQI looks better than it should. There are long gaps in data."
Officials Claim Data is Being Recorded, But Residents Remain in the Dark
Haryana State Pollution Control Board (HSPCB) regional officer Krishan Kumar told TOI: "There is no live display, but the data is being generated every day. LED screens are unable to show data as they were shut down for several months."
While the data may exist in backend systems, the absence of live updates and the strategic misplacement of stations means residents are left unaware of the real air quality they face.
What This Means for Residents and Policy Makers
For residents of Gurgaon, the implications are clear: relying solely on reported AQI figures could underestimate exposure to harmful pollutants. Street-level air is often more polluted than what the data suggests, particularly in areas away from greenery and institutional campuses.
Policy makers and environmental authorities must reassess station placement, maintain real-time displays, and ensure complete pollutant tracking. Accurate and transparent data is critical to informing residents and guiding effective air quality interventions.
Inputs from TOI
Since Diwali, this pattern has been puzzling. Gurgaon has reported only two very poor AQI days, alongside 16 poor days and three moderate days. While wind direction and hyperlocal meteorology can explain short-term variations in air quality, a consistent discrepancy over weeks warrants closer scrutiny of the data, and, crucially, the monitoring stations themselves.
How Faulty Placement of Air Monitoring Stations Skews Gurgaon's Pollution Data
A field inspection on Monday revealed that all five Continuous Air Monitoring Stations (CAMS) in Gurgaon, Vikas Sadan, Sector 51, Teri Gram, Gwalpahari, and Manesar, are poorly positioned. Most are located near thick vegetation or walls, violating Central Pollution Control Board (CPCB) guidelines, which mandate monitors be installed 20-30 metres from trees and 50 metres away from major structures in open, well-ventilated spaces.The placement issue is compounded by inconsistent pollutant recording. Several stations failed to consistently track PM2.5 and sulphur dioxide (SO2), the very pollutants most responsible for NCR’s toxic air. Gwalpahari and Teri Gram, in particular, have recorded incomplete indices over multiple days, artificially improving Gurgaon's average AQI.
Adding to the opacity, LED display boards at all five stations have been non-functional for weeks, leaving residents without real-time air quality information.
Vegetation Around Monitoring Stations Masks True Air Pollution Levels
Over time, lush greenery within government and institutional campuses has grown around these monitoring stations. While greenery is generally beneficial, in this case, it has inadvertently trapped air and absorbed pollutants before they reach the sensors.An official explained: "Vegetation grew, but the monitors' locations stayed fixed. The ambient air at the stations is very different from the road-level air that residents breathe."
This means that the data from these stations does not accurately reflect the air quality that commuters, street vendors, and residents experience daily.
Missing Data Further Distorts Gurgaon's AQI Scores
CPCB real-time data analysis shows that Gwalpahari station failed to record PM2.5 levels for several hours on multiple days this month. Since AQI averages are calculated from available readings, missing PM2.5 data, NCR’s most harmful pollutant, artificially improves Gurgaon's AQI scores.Similarly, Teri Gram station failed to record SO2 data for extended periods. This gaseous pollutant is critical for accurate AQI calculation, and its omission means that Gurgaon's reported air quality appears better than it actually is.
Shubhansh Tiwari, a research associate at the Centre for Science and Environment, said: "The stations are recording partial data and AQI looks better than it should. There are long gaps in data."
Officials Claim Data is Being Recorded, But Residents Remain in the Dark
Haryana State Pollution Control Board (HSPCB) regional officer Krishan Kumar told TOI: "There is no live display, but the data is being generated every day. LED screens are unable to show data as they were shut down for several months."While the data may exist in backend systems, the absence of live updates and the strategic misplacement of stations means residents are left unaware of the real air quality they face.
What This Means for Residents and Policy Makers
For residents of Gurgaon, the implications are clear: relying solely on reported AQI figures could underestimate exposure to harmful pollutants. Street-level air is often more polluted than what the data suggests, particularly in areas away from greenery and institutional campuses.Policy makers and environmental authorities must reassess station placement, maintain real-time displays, and ensure complete pollutant tracking. Accurate and transparent data is critical to informing residents and guiding effective air quality interventions.
Inputs from TOI
