The smog towers are being installed in Delhi on the lines of China, which has experimented
with this technology in its capital Beijing and other cities.
• The Delhi government will study the impact of smog towers on pollution and could add more such structures across the national capital.

• 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.
• 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.
• The smog tower at Connaught Place (CP) is the first of these towers. The second tower, being constructed at Anand Vihar in east Delhi with CPCB as the nodal agency, is nearing completion.
• According to a report by CPCB, an increase of 258% to 335% has been observed in the concentration of PM10 in Delhi since 2009.
• But the most prominent pollutant in Delhi and neighbouring areas is PM2.5
o PM2.5 refers to fine particles which penetrate deep into the body and fuel inflammation in the lungs and respiratory tract, leading to risks of cardiovascular and respiratory problems, including a weak immune system.

• Delhi was the most polluted capital city in the world in 2020 for the third consecutive year, according to a report by a Swiss group (released in March 2021) that ranked cities based on their air quality measured in terms of the levels of ultra fine particulate matter (PM 2.5).

Smog Towers
What is a smog tower?
• Smog towers are structures designed to work as large-scale air purifiers. They are fitted with multiple layers of air filters and fans at the base to suck the air.
• After the polluted air enters the smog tower, it is purified by the multiple layers before being re-circulated into the atmosphere.

Reasons behind high pollution levels

1. Construction work, industrial and vehicular pollution — in and around the city.
2. The situation is aggravated at the start of winter by smoke from stubble-burning in northwestern states, coupled with unfavourable meteorological conditions, such as calm winds, low temperatures, and fewer sunny days.

Measures taken to control pollution:
1. Persuading farmers in Punjab and Haryana to use mechanical alternatives to stubbleburning.
2. Closure of thermal power stations in Delhi.
3. Making industries use piped natural gas.
4. Control measures taken under the Graded Response Action Plan (GRAP) when pollution
levels spike.
• Challenges:
o It may provide immediate relief from air pollution in a small area but they are a costly quick-fix measure with no scientific evidence to back their efficacy in the long term.
o The tower could have an impact on the air quality up to 1 km from the tower.
▪ However, the actual impact will be assessed by IIT-Bombay and IITDelhi in a two-year pilot study  that will also determine how the tower functions under different weather conditions, and how levels of PM2.5 vary with the flow of air.
• Other Steps Taken to Tackle the Problem of Pollution in Delhi:
o Subsidy to farmers for buying Turbo Happy Seeder (THS) which is a machine mounted on a tractor that cuts and uproots the stubble, in order to reduce stubble burning.
o The introduction of BS-VI vehicles, push for electric vehicles (EVs), OddEven as an emergency measure and construction of the Eastern and Western Peripheral Expressways to reduce vehicular pollution.
o Implementation of the Graded Response Action Plan (GRAP). It is a set of curbs triggered in phases as the air quality deteriorates, which is typical of the October-November period.
o Use of Green Crackers.
o Development of the National Air Quality Index (AQI) for public information under the aegis of the CPCB.

Way Forward

• Since there is no scientific evidence that proves its efficiency, governments should instead address root causes and promote renewable energy to tackle air pollution and reduce emissions.
• It will be really unfortunate if other cities decide to follow suit and set up these
expensive, ineffective towers.