Mumbai, Delhi and Kolkata are the three mega cities of the country but the air pollution is much more serious problem in Delhi as compared to the other two. Why is this so? (UPSC 2015)

Delhi’s air pollution is more serious than that of Mumbai and Kolkata because of its geography, weather and emission load. Unlike the two coastal cities, Delhi is landlocked and often acts like a basin, so polluted air gets trapped easily.

• Topography: Surrounded by the Aravallis and influenced by the Himalayas, Delhi has poor natural ventilation.
• Climate: Winter temperature inversion, low wind speed and dry conditions prevent dispersion and washout of pollutants.
• External sources: Smoke from stubble burning in Punjab, Haryana and western Uttar Pradesh adds to Delhi’s pollution in autumn.
• Local sources: Heavy traffic, construction dust, industries and dense urban growth in the NCR raise emissions sharply.

Mumbai and Kolkata benefit from sea breezes and better air circulation, which help disperse pollutants. Thus, Delhi faces both higher emissions and weaker natural cleansing, making pollution more severe and persistent.