MUMBAI: A steady deterioration in Mumbai's air quality has been observed between 2019 and 2023. In contrast, Delhi's and Lucknow's air quality improved, although both cities initially had worse air quality levels than Mumbai. Carcinogenic PM2.5 concentrations during the peak pollution months (October-March) were studied in six major state capitals -- Delhi, Mumbai, Bengaluru, Kolkata, Lucknow, and Patna...