Air purifier for 50 spots in Dhaka, how effective they will be?

While Dhaka North City Corporation (DNCC)’s initiative to set up air purifiers in at least 50 spots around the city to tackle air pollution is commendable as a temporary measure, experts in air quality research argue that it is not a sustainable solution in the long run.  They advise taking coordinated and effective action against root causes for a lasting solution to air pollution.

During a policy dialogue at the Nagar Bhaban of Dhaka North City in Gulshan on Monday, DNCC administrator Mohammad Azaz, unveiled the plan to install these devices. These devices are claimed to have the capacity to purify and cool the air equivalent to that of 100 trees.

The DNCC administrator also added that a sponsor has been found for this initiative, and they have plans to sign agreements with organisations concerned this month. This will not cost the city corporation any money.

Meanwhile, Mohammad Azaz has agreed with the expert opinion. He told Prothom Alo, “We want to run a pilot project and see what the results are. We will discuss it with experts later. If the outcomes are not positive, we will move onto alternative innovations.”

Air purifiers cleanse the air by filtering out tiny dust particles, germs, and harmful gases that contribute to pollution. Typically, these devices use normal filters, carbon filters or electrostatic technology in them.

Experts say, while the larger air purifier units can effectively cleanse the air within a specific radius, their impact basically tends to be confined to limited areas.

According to DNCC sources, 50 fixed air purifier devices of the HDCT 51000 model will be installed across the capital, which is capable of purifying 30,000 cubic feet of air per minute. This device can purify up to 90 per cent of the tiniest airborne particles, as mentioned in the device specifications.

Each of these devices weighs about 1,500 kg, roughly the same as an average Toyota Corolla car. It will require 220 volts of electricity for the device to function, that means it will run on the same voltage used by common household appliances like refrigerators or washing machines.

The specifications of the device mention that these are particularly well-suited for highly crowded areas. According to the World Health Organization (WHO) guidelines, this helps maintain normal levels of particulate matter in the air. The device is capable of sucking out harmful smokes from the air produced by vehicles, industries, and cigarettes.

The Center for Atmospheric Pollution Studies (CAPS) published some findings on 22 April based on an analysis of Dhaka’s Air Quality Index (AQI) data. The centre stated that residents of the capital have been able to breath in clean air only for 31 days in the last nine years (3,114 days).

During this same period, the air quality was unhealthy for 853 days, very unhealthy for 635 days and hazardous for 93 days. CAPs warned that the air pollution level in the country is escalating every year.

The ‘Global Air Quality Report 2024’ from the Switzerland-based organisation IQAir states that Bangladesh was the second most polluted country that year while, Dhaka ranked third among polluted cities.

Researchers working on air pollution have pointed out that it is difficult to bring about a noticeable improvement in the overall air quality by installing this type of air purifiers in a densely populated city like Dhaka. Air purifiers are not among the recognised solutions for tackling air pollution. But these could be installed on trial basis to get temporary relief in a limited space.

Abdus Salam, a researcher on air pollution and a professor at the chemistry department of Dhaka University has commented that installing air purifiers is not an effective measure to prevent pollution.

He told Prothom Alo, “Even the larger countries could not achieve much success with costly initiatives like installing air purifiers. The private companies might be covering the expenses initially, but eventually we would have to buy these at some point. Instead of taking that path, we should focus on identifying and eliminating the sources of pollution.”

Chairman of the Center for the Study of Atmospheric Pollution (CAPS) at Stamford University Ahmad Kamruzzaman said the same thing. He told Prothom Alo, “Air purifiers are not yet a lasting solution at the grassroots levels. This could be an experimental step in some public areas but not a way to solve major problems.”

Professor Kamruzzaman added that considering the socio-economic and environmental aspects of the country, air purifiers are still medical equipment here. Promoting air purifiers separately in a country where 100 per cent of the population is exposed to polluted air is both unfair and discriminatory.

“However, I see this as a positive sign that the city corporation is thinking about air pollution and looking for solutions,” said Ahmad Kamruzzaman.

It was found after installing mega-sized air purifiers in different cities around the world that their impacts are largely limited within local levels. As reported by several Indian media outlets, a 24-metre-high smog tower was set up in Delhi’s Connaught Place in 2021.

While this tower managed to cut air pollution by 70 to 80 per cent within a 50-meter radius, its impact was nearly invisible beyond 300 meters.

A report published by media outlet NDTV on 16 November 2023 showed that the Delhi Pollution Control Committee declared the experimental smog tower in Delhi ineffective at reducing air pollution. At the same time, they also informed the country’s National Green Tribunal that there was no logic behind using costly large air purifiers.

According to the NDTV report, the agency at the time strongly recommended that smog towers are not a realistic solution to the air pollution problem.

In response to the question why air pollution is still there after so much discussion, Professor Abdus Salam said, “There is no solution because effective action is not taken. There is more talk than action and this is the reason behind no relief from air pollution. Powerful committees and task forces are formed when pollution worsens during winter. But the necessary action is not taken.”

This researcher advised identifying the root causes of air pollution and to take effective measures against them. Such effective measures include regulation of old and smoke-emitting vehicles, implementing strict rules on dust control at construction sites, closing down illegal brick kilns, adopting environment-friendly policies in afforestation and urban planning, regular monitoring of pollution levels by establishing air quality monitoring stations etc.