Professor Sachchida Nand Tripathi, atmospheric scientist, member of the steering committee of the National Clean Air Programme (NCAP) and dean of the Kotak School of Sustainability at IIT Kanpur, explains the factors influencing Mumbai’s air pollution and the measures needed to address it.Answer: Several factors could contribute, and it would be premature to conclude that either network is systematically overestimating or underestimating pollution. Private monitors may capture localised hotspots near construction sites and traffic corridors, while government stations may represent different microenvironments. Technology, calibration, maintenance and humidity can also influence readings.The AQI methodology, averaging periods, pollutants included and timestamps must be comparable. The most meaningful assessment would compare PM2.5 and PM10 concentrations over the same time intervals and using the same AQI methodology.Q. Mumbai’s skyline is hazy despite satisfactory official readings. Why?Answer: Visibility and AQI measure different aspects of atmospheric conditions. Humidity can cause airborne particles to absorb moisture and grow, increasing light scattering and making the skyline appear hazy. Fine particulate matter, construction dust and combustion emissions can add to this. However, visible haze alone cannot establish pollution severity or health risk. An electronic board showing a health advisory to people due to air pollution is seen at CSMT in Mumbai on 25 October 2026. (Express Photo by Sankhadeep Banerjee)Q. Can government monitoring stations be relied upon?Story continues below this adAnswer: Government monitors can provide reliable measurements with regular calibration, preventive maintenance and quality assurance. However, instrument malfunction, calibration drift and inadequate maintenance can affect data quality. Calibration records, data validation and comparisons with nearby stations can help assess reliability. Regular comparisons between government and private networks would strengthen public confidence.Q. Does Mumbai’s coastal location protect it from air pollution?Answer: Mumbai’s coastal location does not guarantee good air quality. Sea breezes can redistribute pollutants between coastal and inland areas, while unfavourable wind patterns can cause accumulation. Establishing the reasons for this year’s early deterioration requires analysing rainfall, wind speed and direction, humidity and atmospheric mixing conditions alongside monitoring data.Q. What contributes more to Mumbai’s pollution: weather or human activity?Story continues below this adAnswer: Their relative contributions vary by season. Weather influences how pollutants disperse and accumulate, while major human sources include construction and road dust, vehicular traffic, industries, port and shipping activities, diesel generators and open waste burning. Pollution transported from other regions can also affect Mumbai.Q. Does Mumbai have enough operational monitoring stations?Answer: The network cannot be judged by numbers alone. Mumbai needs representative coverage across residential neighbourhoods, traffic corridors, industrial areas and pollution hotspots. A hybrid network combining reference grade monitors with properly calibrated, low cost sensors can improve coverage.Q. What should Mumbai do to tackle air pollution?Answer: In the short term, authorities should strengthen monitoring audits, ensure data transparency and enforce measures targeting construction dust, road dust, vehicular emissions and waste burning. Longer term, air quality management must be integrated with transport planning, infrastructure development and regional coordination.