India, Jan. 12 -- Cleaner air, usable open spaces and overdue redevelopment have emerged as the key political flashpoints in Mumbai's north-western suburbs of Malad and Kandivali, where civic polls are being fought across a sharply mixed landscape of high-rises, ageing housing colonies and dense slum pockets.

On Sunday, candidates from rival parties fanned out across neighbourhoods, meeting residents and business groups. For the BJP, Union minister Piyush Goyal pitched an ambitious vision: cluster redevelopment of the vast Malvani slums and the gradual shifting of ready-mix cement (RMC) plants out of city limits to curb construction-related pollution.

Goyal visited Adarsh Layout in Malad-Kandivali West, a 25-year-old residential cluster...