The city has 4,578 cellphone towers that are yet to get the BMC's clearance.

Calling it a serious issue, anti-radiation activist Girish Kumar said the "illegal" towers can pose a health hazard to thousands of people. But the Cellular Operators Association of India (COAI) called the towers legal. Its director general, Rajan Mathews, said on Thursday, "Civic permissions for the towers are pending, but we will obtain them in due course. None of the towers poses any health risk."