Experts sceptical of WBPCB’s bio-shield project to stop transboundary air pollution

Experts have pointed out that West Bengal pollution control board’s recent plan to put up a mega green wall to stop air pollutants entering the state from outside, the execution of which may run into several crores and take years, may not serve its purpose.

According to sources, the proposed bio-shield will be put up over around 800 km along Purulia, Birbhum, Paschim Bardhaman and Jhargram to stop transboundary pollutants; which, according to the board, is responsible for around half of the state’s overall pollution load. West Bengal biodiversity board has been entrusted to execute the project.

“Our state pollution control board has come up with the idea of putting up a bio-shield, a massive plantation, along the borders of our state to prevent the incoming air pollutants. It may take a few years to be functional as the trees will take some time to attain maturity” said state environment minister Manas Bhuiya to The Plurals.

“We expect to curb the inflow of transboundary air pollution in Bengal, which is about 50 percent of our overall load, from adjoining states through the bio-shield” said PCB chairman Kalyan Rudra.

Experts are sceptical about the proposal.

“Transboundary movement of pollution can be curbed only with a regional clean action strategy to cut emissions from a large number of pollution sources spread across the region. Green walling with plantations can only filter dust to some extent and that too if it’s hugely extensive” pointed out air emission expert Anumita Roy Choudhury from environmental think-tank Centre for Science and Environment.

“Our research findings show that transboundary air pollutants, especially most toxic PM 2.5, normally moves at least 500 metre above the surface especially during winter; and hence is unlikely to be arrested by bio-shield” explained Abhijit Chatterjee, an air pollution scientist associated with Bose Institute.

“The transboundary pollution flows in between 500 meter and 2 km, beyond the boundary of local pollutants, based on the season and climatic condition; and hence bio-shield has no direct relation in countering any pollution flowing in Bengal from beyond its border,” observed Gufran Beig, an air pollution expert and director of System of Air Quality Forecasting and Research (SAFAR) network set up by Government of India.

However, both Beig and Chatterjee accepted that massive plantations may play a limited role in arresting the pollutants while part of which get landed once mixed with local pollutants; or to address locally generated pollutants.

Plantation experts point out that the mega tree plantation will cost many crores. “Even if we consider trees will be planted at two-meter distance, we are looking at a possibility of planting 4 lakh trees for 800 km in case of one row. Considering the mortality and maintenance, the cost is expected to be around 12 crores. If multiple rows of plants are erected; the cost is likely to increase manifold,” stated wildlife expert Biswajit Roy Choudhury, who heads a non-profit that has planted millions of trees in West Bengal and elsewhere in the country.

Neither PCB nor biodiversity board however came up yet with the project value stating that “the Detailed Project Report is presently being worked out”.

“We are not against tree plantation but would like to know on the basis of what scientific evidence, state board has embarked on such a costly project in the name of countering transboundary air pollution. If it is so useful then why regions like Delhi, which is so much affected by transboundary pollution, is not doing the same. We feel that it will lead to nothing but a complete waste of money” said an environmentalist associated with environment platform Sabuj Mancha.