MUMBAI: The dust from the city’s construction boom is not limited to demolition sites. It is generated when old buildings are pulled down, when foundations for skyscrapers are dug several floors underground, and even when workers cut into walls to lay electrical conduits and plumbing. As redevelopment gathers pace, construction industry stakeholders say existing practices need an overhaul, with better dust suppression, changes to demolition techniques and greater use of precast materials.Senior architect and former president of the Practicing Engineers, Architects, and Town Planners Association (PEATA), Manoj Daisaria, said demolition methods need to move away from using heavy equipment towards dismantling in stages. “When a building is being demolished, the most amount of pollution is generated. There needs to be a change in demolition techniques, with the use of cutters instead of simply smashing structures to pieces,” Daisaria said. “In the early days, particularly in locations near Fort and other parts of south Mumbai, buildings had tiled roofs and structures made entirely of bricks. When these buildings had to be demolished, bricks and tiles were removed one by one by hand. We need to replicate this. It will be more time-consuming and costly in terms of manpower, but it should reduce pollution significantly.”Daisaria identified excavation as another major source of dust, particularly as new buildings incorporate multiple basement levels. “Today, with the growing number of skyscrapers, excavation can extend five or six floors underground, generating tremendous amounts of dust,” he said.He suggested making netting mandatory at construction sites during excavation, along with regular fogging. “Currently, nets aren’t mandated during excavation, but introducing them should help. These measures will not increase costs too much, but ultimately, the additional expense will have to be absorbed because it is the need of the hour,” he said.Structural consultant R C Tipnis also identified the demolition of older buildings and structures as a major source of dust pollution. He said curbs or restrictions on demolition were needed, along with a standardised model and greater self-discipline among those involved.Dust generation continues even after a building’s structure takes shape. Former contractor Mihir Setia highlighted jari, or grooving, a process in which workers cut channels into walls to accommodate electrical conduits and internal plumbing.“The days that generate the most dust during construction are those when grooving, or jari, is carried out. So, when you cut into these concrete blocks, fly ash spews out,” Setia said.He added that controlling dust during this activity presented a practical challenge.Developer Rajesh Jain said builders should use precast construction materials, which would help reduce pollution at construction sites. “Builders will adapt and they have the capacity to do so. The cost increase is irrelevant in the long term, as most builders are used to varying costs and prices,” he said.Speaking about the BMC’s dust mitigation guidelines, Jain said they were suited only to developed cities such as New York and London. “Half of our city is a slum that needs to be developed first, and pollution is a by-product of this process,” he said.Jain said the bigger problem lay in the priorities and incentives set by the government. “The govt is prioritising revenue generation for itself through the sale of additional FSI, which is driving the construction boom. Instead, it should focus on two main priorities: the reconstruction of ageing buildings built before 1940 and slum development, and stop the sale of additional FSI. The crux is that we are following a revenue-based DP and not a density-based model. This only incentivises revenue generation for the govt through additional FSI sale,” Jain said.
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