Mumbai, Dec. 19 -- The Brihanmumbai Municipal Corporation (BMC) has proposed a fivefold hike in penalties for violating air pollution norms, raising the minimum fine from Rs.10,000 to Rs.50,000. "We have proposed increasing the penalty to act as a stronger deterrent against construction sites that cause air pollution," said deputy municipal commissioner (environment and climate change) Avinash Kate, adding that higher penalties are intended to ensure stricter compliance with pollution control norms at construction sites. The proposal has been submitted to civic commissioner and administrator Bhushan Gagrani for approval. Currently, the BMC is monitoring 1,954 ongoing private construction sites through 94 flying squads. Each squad includes assistant engineers, nuisance detectors and a sub-engineer from the environment and climate change department. On Thursday, the civic body issued show-cause notices to 20 construction sites and stop-work notices to 18 sites. Between December 1 and 16 this year, the BMC had already issued 353 show-cause notices and 121 stop-work notices against polluting sites. According to the civic body, these measures have led to a significant improvement in air quality compared to the beginning of December last year. During the same period last year, the city's Air Quality Index (AQI) ranged between 158 and 167, while this year it remained between 105 and 113. On Thursday the city's air quality remained in the moderate category, with an AQI of 138, according to data from the CPCB. Byculla and Deonar recorded an AQI of 149, while Malad West stood at 148. The Bandra-Kurla Complex and Navy Nagar-Colaba recorded an AQI of 144 each. Relatively cleaner air was reported in Borivali East with an AQI of 110, while Mulund West recorded the lowest AQI at 64....