Mumbai air pollution can be significantly worse on upper floors of high-rise buildings than at ground level, according to a study by the Mumbai Ecological Research and Analysis Group (MERAG), which recorded particulate levels as much as 40% higher at elevated residential floors in Wadala.
The study was conducted across major residential complexes in Wadala between February and May 2026. Researchers used continuous multi-floor sensor devices and real-time wind tracking to examine how fine particulate matter, coarse dust and gaseous indicators changed with elevation.
The findings challenge the common assumption that moving above street-level traffic automatically provides cleaner air. MERAG reported a persistent positive vertical gradient, meaning pollution levels generally increased with height. The ratio between particulate concentrations on higher and lower floors peaked at 1.40 in March, indicating that upper levels recorded 40% higher pollution during that period.
Sensors were installed from the second floor to the 26th floor. The study monitored air quality across different elevations while also tracking wind conditions, allowing researchers to examine how pollution moved through the high-rise environment rather than measuring only street-level exposure.
According to the report, one possible explanation is that emissions from distant industrial sources and factory chimneys travel horizontally through the atmosphere and reach taller buildings without first settling near the ground. This means that the pollution affecting upper-floor residents may not come only from nearby road traffic or activities at street level.
MERAG also linked the pattern to the wind behaviour created by clusters of tall buildings. The buildings can generate small-scale wind eddies and recirculation, potentially trapping smoke and fine dust at higher elevations instead of allowing the pollutants to disperse.
The convener of MERAG said the results showed pollution was “systematically higher on each floor” covered by the sensors. The convener added that a sensor installed on the 40th floor might have recorded even higher levels, although the study findings supplied in the report extend only to the 26th floor.
The Wadala study does not establish that every high-rise in Mumbai has higher pollution at upper levels, nor does the supplied report provide a citywide comparison or health-impact assessment. Its immediate significance lies in showing that building height, surrounding industrial activity and local wind patterns can interact in ways that make air quality within a residential tower highly uneven. Further monitoring would be required to determine whether the pattern is repeated across other parts of Mumbai and under different seasonal conditions.
