Delhi

In a flux over smog towers

Vehicles moving amidst a thick layer of smog in Delhi.

Vehicles moving amidst a thick layer of smog in Delhi. | Photo Credit: Sushil Kumar Verma

A walk of up to one km in three different directions from the smog tower in Connaught Place with a handheld air quality monitoring device has revealed fluctuating levels of the chief pollutant, PM 2.5. What is interesting is while the air closest to the tower should be cleanest, the device recorded the opposite in several instances — falling pollution levels as one moved away from the tower.

The data was collected by this reporter on an air quality monitor of ‘Prana Air’ provided by the Council on Energy, Environment and Water (CEEW), and was shared with three experts, who observed that multiple factors influence the air quality at the height where the readings were taken. While a detailed study factoring in all sources of pollution is required to arrive at the final conclusion, the experts were unanimous about increase in levels of pollution as one moves away from the tower in an ideal situation.

Pollution woes:  The smog tower at Connaught Place; (above) vehicles moving amidst a thick layer of smog in Delhi.

Pollution woes: The smog tower at Connaught Place; (above) vehicles moving amidst a thick layer of smog in Delhi.

 

A paradox

Anju Goel, a Fellow at the Energy and Resources Institute (TERI), said the air closest to the tower should be the cleanest because it sucks in the dirty air from the top of the tower and releases filtered air near the surface through fans on the sides of the tower.

“Whereas the value of PM 2.5 decreased as you moved away from the tower, which is in contradiction to normal scenario. The readings indicate the efficiency of the smog tower is not enough to clean the air to the extent it is needed. At the height of 1.5 to two metres from the surface, it is a mixed zone with high turbulence. Your readings also fall under this category,” she responded.

When approached, a Delhi government official held that multiple factors could be responsible for such variations and therefore, the data is not showing a clear trend of reduction in pollution with distance from the tower.

This reporter walked towards RML Hospital, where the value of PM2.5 was 327.5 ug/m3 at 50 metres from the tower and 325 at 100 metres from the tower, but it dropped to 301 at 300 metres and raised slightly to 307 at 500 metres. Towards Connaught Place also a similar trend was observed, but towards Parliament House, there was a rise after the fall in values. The readings were taken on December 25, when the city’s air quality was ‘severe’.

Multiple monitors

A CEEW Fellow, Karthik Ganesan, said, multiple monitors should be ideally used to measure pollution at all points at the same time to get accurate results.

“If at all the smog tower has an impact, then the pollution should increase as you move away from the tower. But the recorded values show a decrease. Which means that at different points along the road, there is an impact of different sources of pollution. This also shows that the impact of the smog tower is negated by all these sources,” Mr. Ganesan said.

Anumita Roychowdhury, Executive Director of Centre for Science and Environment, a research and advocacy NGO, said focus has to be on reducing emissions at sources than attempting to purify dynamic and voluminous air in outdoor conditions. She wondered how tiny whiffs of purified air mixed with polluted air could help to improve the quality of air in general. “Instead of spending ₹40 crore on two towers, the government could have spent the funds on several other options such as replacing the small and polluting industrial boilers or the chulhas burning dirty fuel in poor households,” she said.

Not viable

The experts reiterated the smog towers are not a viable method to clean city’s air. The pilot project spending ₹20 crore was constructed following a Supreme Court order and was inaugurated by Chief Minister Arvind Kejriwal on August 23, who had promised then that data analysis would begin immediately and a detailed performance report would be obtained within two years after the performance is examined by experts. Also, he said the government would get monthly trends to analyse how efficiently the tower is working. Earlier, the government had talked about 80% pollution reduction at inlet and outlet of the tower but never mentioned about the effect of distance from the tower.

On October 1, Environment Minister Gopal Rai said that a committee constituted to look into the efficacy of smog tower would submit three reports to the government at the end of every three months.

But the government is yet to release any data on what impact the smog tower has made on the quality of air when at a distance from the tower.


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Printable version | Feb 13, 2022 8:40:08 am | https://www.thehindu.com/news/cities/Delhi/in-a-flux-over-smog-towers/article38289039.ece