By Nitin Bansal
It is estimated that nearly 70 per cent of the buildings that will exist in Indian cities by 2030 are yet to be built. Which means that India is unlikely to lose its infamous badge of “country with the deadliest polluted air” any time soon -- unless it takes some quick counter-measures.
The challenge lies in maintaining the construction momentum while following time-tested practices. Surely, construction projects like the Metro, roads and residential homes need to be undertaken on high priority. For this, sand, gravel, stones, bricks and more will inevitably travel in open trucks criss-crossing crowded cities -- and the debris spilled en-route lodges in the human respiratory system, causing insidious life-threatening lung diseases. Construction was banned in the Indian capital for a week last year, but this is not nearly enough.
As the head of a firm that builds homes on residential plots, I have increasingly felt the need to do whatever possible to reduce the spread of construction debris and material into the air we breathe. We have spent considerable hours looking for workarounds and alternatives that will make some difference -- because every little bit counts.
Of the sources of construction pollution, the biggest culprit is sand. After all, it comes in a loose format. Truck after truck comes in and dumps enormous loads of sand at the construction site. It often sits there, waiting to be used, and all it takes is a bit of breeze for it to add to air pollution.
A four-storeyed, multi-family residential home on a typical 200 square yard plot requires something in the region of 85 trucks of sand -- enough to fill a dozen bedrooms from top to bottom. Obviously, there must be some thought given to reducing the very use of sand in construction.
Sand is used for different purposes during construction. One of these is concreting. Instead of creating concrete at the site (often referred to as site-mix concrete), explore ordering ready-mix concrete (RMC).
It’s the same with wall plaster. Dry, ready-mix plaster available in bags can be mixed with water and used for plastering. This eliminates the pollution caused as a result of transportation or even when material is sitting at the site -- all packed. We use these alternatives for all the homes we build, reducing the use of loose sand by 80 to 90 per cent.
With thousands of old homes, especially those built in 1960s and 1970s, needing rebuilding, demolition activity and debris transportation are yet another source of air pollution. Try covering the demolition site with a “shade net” from all sides, including the top. It is a solution worth implementing as it contains the spread of material into the air. But the “shade net” has to be sealed on all sides to be effective.
Today, green “shade nets” can be seen in many places where major renovation is happening, but typically only some parts of the building are covered up to prevent them from being an eyesore. I would recommend a fully-enclosed construction site. Workers will, of course, need to work with masks within this enclosure.
A great deal of water is typically used during construction, specially to cure material such as bricks, concrete slabs or on plaster which also needs moisture for cement to gain strength. This water then runs polluted into drains, adding to the general pollution. Spraying a layer of curing compound does away with the need to keep the concrete slabs under water for a couple of weeks or spraying brick walls and cement plaster with water.
Use of Autoclaved Aerated Concrete (AAC) blocks rather than red bricks is better as they don’t need to be soaked before use. Similarly, readymade plaster means that water doesn’t have to be poured over walls and so on. Materials that come in closed bags reduce the probability of their mixing with the air.
Using RMC rather than sand, aggregate and cement mix on the site actually works out to the same in terms of cost, as does the use of gypsum plaster compared with on-site plaster and putty. The price AAC blocks is comparable to red bricks. Readymade plaster, however, does cost approximately double. The savings in terms of better health for all concerned, however, are inestimable.
The Ministry of Environment notified a Graded Response Action Plan to fight air pollution in Delhi and the National Capital Region area last month. With the plan in place, measures such as odd-even rules and restrictions on construction work will be automatically implemented whenever the level of PM2.5 breaches 300 micrograms per cubic metre and PM10 levels stay above 500 micrograms per cubic metre for two days in a row.
Unless the construction industry takes action to reduce its contribution to air pollution, it’s bound to lose out on the completion of its projects.
