Delhi was identified as India's most polluted megacity in 2025, with an annual average PM2.5 concentration of 96 μg/m³, significantly exceeding national and WHO safety standards. A CREA report indicates that while local sources like transport (46%) and industry (22%) contribute, a substantial 65% of Delhi's pollution originates from NCR districts and beyond. Ghaziabad and Noida also reported high pollution levels.