Morning Rain Cleanses Kolkata's Air, Delivers Best AQI Since Early November
An early Tuesday morning shower swept across Kolkata, acting as a natural cleanser that scrubbed layers of grime from the city's weary skyline. This rainfall delivered the best air quality Kolkata has experienced since November 3, providing a much-needed respite for residents.
Significant Improvement in Air Quality Index
The rain effectively rinsed dust-laden tree leaves, soaked the parched topsoil, and settled road dust that had persistently elevated pollution levels during a prolonged dry spell. For the first time in months, Kolkata's overall Air Quality Index (AQI) remained in the 'satisfactory' range (51–100) throughout the entire day. This marked a significant improvement after weeks of readings stuck in the 'moderate' range, offering a rare spell of clean, breathable air amid a recent spike in respiratory ailments.
Dramatic Transformation in Green Areas
The transformation was most dramatic around the Maidan, often referred to as the city's lung, where the extensive 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 in air quality.
A pollution control board scientist explained, "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." The long dry spell prior to Tuesday had left the topsoil extremely dry and grassless in many areas, allowing fine particles to become airborne easily. Vehicular movement had continuously resuspended road dust, preventing the AQI from dipping below 'moderate' levels.
Specific AQI Improvements Across Kolkata
Tuesday's rainfall effectively reversed that trend, with leafy and grassy zones consistently recording better air quality than densely built-up areas. For instance:
- 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 also entered the satisfactory range by evening, with readings improving from 117 to 99.
In more built-up zones, the improvement was evident but 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.
- RBU (B T Road) saw levels fall from 157 to 113 — still 'moderate' but significantly cleaner than morning readings.
Experts Caution on Temporary Nature of Relief
Environmental experts, however, cautioned that such relief is often temporary unless supported by sustained dust-control measures and increased green cover. They emphasized the need for ongoing efforts to maintain improved air quality levels in the city.
