Chandigarh is the first planned modern city in India. But with PM2.5 air pollution levels nearly 8 times higher than the WHO recommended limit, the city has turned to a novel solution to help improve its air quality: smog towers. The question is, will Chandigarh’s smog tower help improve air quality?
Chandigarh’s Smog Tower
With a height of 25 m, the Chandigarh smog tower is one of the tallest towers in India. The smog tower first takes the polluted air into its mist chamber where it sprays the dirty air with mist. The polluted water is then drained and collected with a tube and purified air is released outside. This tower also uses an air quality monitor at the inlet and outlet to display the air quality. Chandigarh Pollution Control Committee claims that this smog tower would cover around a 500-meter radius.
Will Chandigarh’s Smog Tower Work?
This Chandigarh smog tower isn’t the first outdoor air purification project. Similar smog towers have been installed in Connaught Place, Delhi, and Xian, China.
Dutch artist Daan Roosegaarde built an ionizing tower in Beijing and Tianjin, claiming it would clean air the air pollution outdoors. But independent tests of the air filter tower found it 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 is more art than science.
Real-Data: Effectiveness of Outdoor Air Purifiers
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.
At the beginning of the test, the outdoor PM level was 89 ug/m3. Then we turned on the air purifier 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 PM 2.5 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.
How is Chandigarh’s Air Quality?
Chandigarh’s air quality improved last year compared to 2019 (38.3 ug/m³ vs 59.1 ug/m³) due to a strict COVID19 lockdown with strict restriction of movement of vehicles, construction, and industrial activities. However, it is still 8 times higher than the recommended WHO annual limit for PM2.5.
Chandigarh’s air pollution primarily comes from heavy transport vehicles, industrial pollution, and vehicular emission. Seasonal stubble burning is also another problem during the winter when air pollution is at its worst. Data suggests that temporary solutions like smog towers will not help improve Chandigarh’s air pollution. Rather, the focus should be put on long-term solutions that fix the root of the problem. The government should focus on promoting green transport and use more renewable energy sources to reduce emissions.
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
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