Rain washes Kol clean, city records best air since Nov 3 after sharp AQI improvement

Kolkata: An early Tuesday morning shower swept across Kolkata like a natural cleanser, scrubbing layers of grime from the city's tired skyline and delivering the best air quality it saw since Nov 3. The rain rinsed dust-laden tree leaves, soaked the parched topsoil that steadily released fine particles into the air, and settled road dust that stubbornly kept pollution levels elevated through a prolonged dry spell.For the first time in months, Kolkata's overall Air Quality Index (AQI) remained in the ‘satisfactory' range (51–100) through the day — a significant improvement after weeks of readings stuck in the ‘moderate' range. The respite came amid a recent spike in respiratory ailments, offering residents a rare spell of clean, breathable air.
The transformation was most dramatic around the Maidan, often called the city's lung, where the green cover and open spaces amplified the rain's cleansing effect. Continuous Ambient Air Quality Monitoring Stations (CAAQMS) at Fort William and Victoria Memorial Hall recorded some of the sharpest improvements. "The smart shower cleansed the thick layer of dust from the leaves, enhancing their ability to absorb pollutants from the ambient air. Moreover, road dust resuspension was neutralised," said a pollution control board scientist. The long dry spell before Tuesday left the topsoil extremely dry and grassless in many areas, allowing fine particles to become airborne easily. Vehicular movement kept resuspending road dust, preventing the AQI from dipping below ‘moderate' levels.Tuesday's rainfall effectively reversed that trend. Leafy and grassy zones consistently recorded better air quality than densely built-up areas. Rabindra Sarobar in south Kolkata, another green pocket, saw its AQI improve from 120 in the morning to 90 by late afternoon, moving from ‘moderate' to ‘satisfactory'. Salt Lake, too, entered the satisfactory range by evening, with readings improving from 117 to 99.In more built-up zones, the improvement, though evident, was less dramatic. Ballygunge's AQI dropped from 138 at 7 am to 107 at 5 pm, remaining in the ‘moderate' category. Jadavpur improved from 135 to 105, while RBU (B T Road) saw levels fall from 157 to 113 — still ‘moderate' but significantly cleaner than morning readings.Environmental experts, however, cautioned that such relief is often temporary unless supported by sustained dust-control measures and increased green cover.