On a recent day when Delhi’s AQI soared to around 345 (“very poor”) and Noida’s hovered near 318, Gurgaon’s meter surprisingly read only 221 (“poor”) — yet residents felt the air was just as foul.

1. Faulty monitoring station placement – All five continuous air-quality monitors in Gurgaon are located near dense vegetation or close to large walls/buildings, which violates guidelines requiring open, well-ventilated placement. The surrounding greenery or structures can absorb or deflect pollutants before sensors detect them.
2. Data gaps and incomplete pollutant recording – Several stations in Gurgaon have failed to log key parameters (such as PM2.5 or SO₂) for hours or days. When readings are missing, AQI calculations can be artificially lower because fewer pollutants are factored in.

Meteorological factors also offer a partial explanation: Gurgaon lies on the southwestern fringe of the NCR and benefits from slightly different wind directions and faster pollutant dispersion over the nearby Aravalli hills. However, experts caution not to over-interpret this “advantage” — the monitor network is thin (only 5 stations vs over 30 in Delhi), and a single poorly placed sensor can skew city-wide averages significantly.