Just one day after authorities revoked the stringent GRAP-3 anti-pollution curbs, Gurgaon's air quality took a sharp turn for the worse on Saturday. The city slipped back into the 'poor' category, dashing hopes of sustained clean air after a brief period of improvement.
AQI Deteriorates Across Monitoring Stations
The city's overall Air Quality Index (AQI) was recorded at 244, a significant decline from Friday's reading of 187. On Friday, the air had briefly improved to the 'moderate' category, offering respite after more than two months of consistently 'poor' to 'very poor' conditions. The deterioration was widespread across most monitoring stations.
Vikas Sadan recorded the most severe air quality with an AQI of 295. It was followed by Teri Gram at 245 and Gwalpahari at 228. Sector 51 was the sole station to remain in the 'moderate' bracket, registering an AQI of 190.
Weather Conditions to Blame for Pollutant Build-Up
According to forecasts from the System of Air Quality and Weather Forecasting and Research (Safar), the situation is likely to worsen in the coming days. Meteorological conditions are highly unfavourable for the dispersion of pollutants.
Dispersion is expected to remain limited due to weak winds and poor ventilation. Predominant surface winds in the morning are forecast to blow from the west at speeds below 5 kmph. While wind speeds may increase slightly in the afternoon, they will remain below 15 kmph and shift to the northwest. By evening and night, winds are predicted to weaken again to below 5 kmph.
Understanding the Ventilation Index
The predicted maximum mixing depth is around 1,200 metres, while the ventilation index is expected to be approximately 4,500 m²/s. Safar experts have noted that a ventilation index below 6,000 m²/s, when combined with an average wind speed under 10 kmph, creates an environment that traps pollutants. This condition is highly unfavourable as it prevents the dispersal of harmful particles, increasing the likelihood of a dangerous build-up near the surface where people live and breathe.
The rapid return of poor air quality underscores the fragile nature of Gurgaon's pollution problem, which remains heavily dependent on favourable weather for relief, even after temporary regulatory measures are lifted. Residents are advised to take necessary precautions, especially those with respiratory conditions.
