Bangalore Gets Its First Smog Tower, But Does It Work?

Although Bangalore is one of India’s fastest-growing cities, this has come at the cost of more air pollution. According to Greenpeace South Asia in 2020, an estimated 12,000 people in Bangalore died due to air pollution. To help improve Bangalore’s air pollution, the city has installed its first smog tower. Will this smog tower help improve Bangalore’s air quality?

How the Bangalore Smog Tower Works

Unlike typical air purifiers that rely on effective HEPA filters, the Bangalore smog tower takes a different approach. The creator of the tower, Nutan Labs, states their outdoor air purifier uses a four-step process to purifier Bangalore air. Much of this technology is based on newer research and technology and therefore lacks a long track record of effectiveness.

Will Bangalore's smog tower work?

Step 1: MOFilter

The first step is a “non-reactive sandwiched metal mesh framework”. The type of filter, also known as “MOFilters”, was developed recently by researchers to mimic a HEPA filter for larger industrial uses. Data shows this type of filter can be effective at removing dangerous pollutants such as PM2.5, but data is lacking on how its effectiveness over time with use.

Step 2: Nanoclusters to neutralize dangerous gases

The second step attempts to neutralize dangerous gases using nanoclusters. The idea is for the nanoclusters to react with dangerous gases such as SOx, NOx, COx and convert them to less harmful compounds. Although there is some evidence this technology can help reduce dangerous gases in the air, it is a relatively new technology for air purification with a limited track record. 

Step 3: Membrane coated with nanoparticles

The third step seems to work in a similar way to step 3. The company does not release too much information, other than the following:

Again, real-world data is not provided to back up the effectiveness.

Step 4: Activated Carbon

Although the company does not state the technology used in step four for VOC removal, they show what looks to be a pile of activated carbon for stage 11. This technology has a long track record for absorbing dangerous VOC gases from the air. At Smart Air, we have tested the effectiveness of activated carbon with our own purifiers, which showed VOC levels dropping significantly with use.  

The problem with activated carbon is that at a certain point it becomes saturated and can not absorb any more gases. This could happen very quickly in an outdoor environment and may need to be replaced frequently.

How Bangalore's smog tower works

Will the Bangalore Smog Tower Work?

This isn’t the first outdoor air purification project. Similar smog towers were installed in Connaught Place, Delhi, and Xian, China. Data on the effectiveness of these “smog towers” was not promising.

Dutch artist Daan Roosegaarde built an ionizing tower in Beijing and Tianjin, claiming it would clean the outdoor air. Independent tests found the air filter tower was not providing clean air even within 10 meters of the tower. Even a careful look at the team’s own modeling estimated only a 20% drop among large particles (PM10, not PM2.5), assuming zero wind, and only up to 20 meters from the tower. Thus, the tower was more art than science.

How Bangalore's smog tower works

Real-life Effectiveness of Air Purifiers in Outdoor Settings

To understand the effectiveness of an air purifier in an outdoor setting, the CEEW team carried out a real-world test using Smart Air’s Blast Mini/Ladakh Mini air purifier. With a CADR of 585 m3/h, the purifier cleans significantly more air than the typical home air purifier. During this real-life test, two air quality sensors were used to measure the PM2.5 levels at varying distances of 2 feet, 4 feet, and up to 12 feet from the air purifier.

Does an outdoor air purifier work?

Image Courtesy: CEEW

At the beginning of the test, the outdoor PM level was 89 ug/m3. Then the Ladakh Mini air purifier was turned on for 1.5 hours. After this, we measured air quality at different distances to determine the effectiveness of the air purifier in an outdoor environment. 

We first measured at a distance of 4 feet in the line of airflow. This reduced pollution levels to 51-53 ug/m3. Next, at a distance of 12 feet, the PM2.5 level was reduced to 62-64 ug/m3. Towards the end of the experiment, we turned the air purifier off and the PM2.5 levels reached ambient levels immediately

Where Does Bangalore’s Air Quality Stand Among Major India Cities?

Bangalore’s air quality improved last year compared to 2019 (27.5 ug/m³ vs 32.6 ug/m³). This was due to strict lockdown and restriction on the vehicular moment, construction, and industrial activities. However, PM2.5 pollution levels are still three times higher than the recommended WHO annual limit. In addition, Bangalore saw an increase of 90% in NO₂ levels in 2021 compared to 2020.

Air Pollution in Bangalore

Bangalore air pollution problem stems from industrial pollution, construction, and vehicle emissions compared to seasonal stubble burning, industrial and waste burning in Delhi. Data suggests temporary solutions like smog towers will not help improve Bangalore’s air. Rather, it would require curbing air pollution at the source. Also, stricter environmental laws and enforcement are needed to improve the air quality in Bangalore. Lastly, more air quality monitoring stations in the city’s hotspots, power stations, and industries would help better monitor the air pollution problem in real-time.

Studies Document Protective Effects of Purifiers, Masks

Despite the harms of PM2.5, studies have found that wearing masks prevents harmful effects on blood pressure and heart rate variability. Similarly, placebo-controlled studies of air purifiers have found that reducing particulate in the home prevents harm to blood pressure, inflammation, and immune response—even among young, healthy twenty-year-olds.

How I Protect Myself

Smart Air is a certified B Corp committed to combating the myths big companies use to artificially inflate the price of clean air. To help people living in polluted cities protect themselves, Smart Air provides empirically backed, no-nonsense purifiers and masks, thereby helping to lower the cost of clean air.

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