Smog tower: How it works

Polluted air is sucked in at a height of 24 m, and filtered air is released at the bottom of the tower, at a height of about 10 m from the ground. 

• When the fans at the bottom of the tower operate, the negative pressure created sucks in air from the top. 
• The ‘macro’ layer in the filter traps particles of 10 microns and larger, while the ‘micro’ layer filters smaller particles of around 0.3 microns.
• Filtered air is released at the top of the tower.

Likely impact:

Computational fluid dynamics modelling by IIT-Bombay suggests the tower could have an impact on the air quality up to 1 km from the tower. 

• The actual impact will be assessed by IIT-Bombay and IIT-Delhi in a two-year pilot study.
• It will determine how the tower functions under different weather conditions, and how levels of PM2.5 vary with the flow of air.
• An automated Supervisory Control and Data Acquisition (SCADA) system in the tower will monitor air quality. 

Supreme Court order:

In 2019, the Supreme Court directed the Central Pollution Control Board (CPCB) and the Delhi government to come up with a plan to install smog towers to combat air pollution.

• The court was hearing a matter related to air pollution in the national capital due to stubble-burning in Punjab, Haryana and Uttar Pradesh.
• IIT-Bombay then submitted a proposal for the towers to the CPCB. 
• In January 2020, the Supreme Court directed that two towers should be installed by April as a pilot project.

Need for:

A report by the CPCB noted that, Since 2009, an increase of 258% to 335% had been observed in the concentration of PM10 in Delhi, a 2016. But the most prominent pollutant in Delhi and neighbouring areas is PM2.5.

Source: Indian Express