Not without fallouts

The Supertech Twin towers in Sector 93A of Noida, Uttar Pradesh, were demolished by controlled implosion at 2.30 pm on August 28, 2022. Their being located in a residential neighbourhood of Noida makes it even more essential to introduce interventions to mitigate pollution and waste, post-demolition.

The operation was carried out by Edifice Engineering based in Mumbai, and South African company Jet Demolition. The demolition was done by a method known as 'waterfall technique' to minimise damage to the surroundings.

But the demolition has resulted in 80,000 tonnes of construction and demolition (C&D) waste. Some 50,000-55,000 tonnes will be used for filling the site and dumped at designated areas. The rest will be sent to a C&D plant for processing.

This demolition has also produced large amounts of dust. Heavier dust particles will settle down soon but the light particulate matter (PM) will probably remain in the air for weeks.

The settling of the dust particulate will also depend on wind speed and wind direction. Dust will also remain in the air because of loading and unloading of trucks for clearing the debris.

The Air Quality Index (AQI) bulletin issued by the Central Pollution Control Board at 4 pm August 28 mentioned Noida's AQI to be at 120. This is considered to be 'moderate'. Delhi, located just across the Yamuna, had an AQI of 119, which is also categorised as 'moderate'.

Impact on health

However, a more detailed analysis of pollutants and chemicals should be done to understand the health hazards of such a large-scale demolition by explosives. The immediate vicinity of the site after the demolition witnessed a huge cloud of dust, which soon spread to a vast area.

There are various health effects that can befall people in the vicinity, like respiratory issues, skin ailments, as well as allergic disorders. There is an increase in lead, silica and asbestos in the atmosphere and a tremendous amount of PM10 and PM2.5 particles.

Increased lead exposure may lead to headache, tiredness, irritability and constipation, silicosis, etc. Silt accumulation in drainage systems can lead to problems like water-borne and parasite diseases.

Immediate mitigation measures

The Noida Authority has been reported to have provided water tankers, mechanical sweeping machines and sanitation staff, as well as air quality monitoring at and near the building site.

Anti-smog guns and water sprinklers have been in use in the area after the demolition to minimise the spread of PM in the atmosphere.

Dust machines have been installed at the site for monitoring pollution levels after the demolition. Layers of tarpaulin, synthetic sheets and protective covering material have also been put on each floor of the towers by the demolition team to minimise the impact of dust, noise and vibrations.

The Noida Authority is also monitoring AQI levels post-demolition. The concerned authorities had given an NOC for the demolition to go ahead and post the demolition, the standard protocols for disposal of debris will be followed according to The Construction and Demolition Waste Management Rules, 2016.

Apart from impact on human health, the demolition is expected to affect the local flora and fauna in more ways than one, experts have told Down To Earth.

Impact on flora

The towers were located in a residential neighbourhood with large green spaces and significant tree cover. The post-demolition dust has engulfed nearby trees and vegetation.

Sprinklers are being operated, water has been sprinkled on trees, vehicles and smog guns were being operated to settle down the dust which may have localised benefits but seem inadequate to douse the dust and other fine debris.

Dinabandhu Sahoo, director of Centre for Himalayan Studies, Delhi University (DU) and senior professor, Department of Botany, DU, explained how flora would be hit.

"When you have such fine particles that form in the aftermath of the implosion, all leaves and the canopy will be covered completely. So, the rate of photosynthesis will come down. Once that happens, the plants' productivity will reduce," he told DTE.

If there was continuous rain, the dust would be washed away and percolate into the soil and remain there for some time.

"But it will take a long time for the plants and trees to be rejuvenated. Birds and insects, especially pollinators, will be affected. The only way this situation can be changed for the better is sprinkling water continuously," Sahoo noted.

Impact on fauna

The area where the implosion took place is home to several types of birds and some mammalian species as well. Most experts DTE spoke to, said these would leave the area for some time and come back later.

"That place will become devoid of any kind of biodiversity. There will be a drastic collapse in populations," Sohail Madan, assistant director with the Bombay Natural History Society, said.

He added that it was difficult to talk about long-term impacts at the moment. "I am not sure if materials like asbestos or other harmful substances were used in the construction of the buildings. If arsenic and mercury were used, there would be long-term impacts on humans as well as wildlife," Madan said.

He also highlighted that the area where the implosion took place as well as those in its vicinity are very rich in bird life. "There are mostly normal garden birds there. Owls, barn owls, spotted owlets, scops owls as well as water birds, will all be impacted," Madan added.

Faiyaz Khudsar, Delhi-based wildlife biologist, pointed to the noise created by the implosion.

"Studies have shown that birds living within cities change their vocalisation due to the noise around them. Vocalisation is used by birds for breeding and protection. But they change the pitch and quality of their vocalisation due to noise pollution," he said.

Khudsar added though that the noise in this case was short-term hence birds and mammals in the area would leave for some time.

Certainly, mammals would be affected like their avian counterparts. Murali Krishna Chatakonda, assistant professor, Amity Institute of Forestry and Wildlife, Amity University, Noida, talked about the impact on rodents like squirrels.

"There will definitely be a negative impact on squirrels though they are more used to urbanisation. Squirrels have respiratory systems similar to humans. So, the particulate matter floating for weeks will affect them as well," Chatakonda said. He added that squirrels too would leave the area but would come back once the dust settled.

Khudsar said jackals were common in the vicinity of the Yamuna, which is located quite near the demolition site.

"Here, they get plenty of food in the form of rodents, berries called locally as jharberi (Ziziphus nummularia), the fruit of the wild jujube plant as well as carrion," Khudsar said.

"The nilgai antelope is also found in the area as it is a denizen of the Yamuna floodplain, where there are hardly any natural predators to hunt it," he added. DTE

Views expressed are personal