WAYU: What do we know?

On September 26, 2018, Dr. Harsh Varshan inaugurated WAYU, a device designed by CSIR-NEERI. WAYU (Wind Augmentation PurifYing Unit) — is expected to keep an area of 500 sq m around the unit clean, and such devices are being installed at busy traffic intersections. Each unit costs INR 60,000, and monthly maintenance costs are expected to be under INR 2000. The plan is to install 54 such monitors across Delhi by October 15, 2018

What is WAYU?

“The device, which brings together developments in chemistry, physics and micro-meteorology on a single platform, consists of two stages. In the first stage, a fan sucks air around the device and pollutants like dust and particulate matter are separate using three filters of different dimensions. After this, the air is led into a specially designed chamber where carbon monoxide and hydrocarbons content in the air are oxidized into less harmful carbon dioxide using activated carbon coated with titanium dioxide. The oxidation is supported by two ultraviolet lamps (UV). The purified air is then ejected with force into the atmosphere so as to help dilute pollutant content in the outside air.”

Source:  The Hindu Businessline

More on this story here , here and here (Hindi).

However, this comes after a trial in Mumbai in 2017 was not found to be very effective:

A week after outdoor air purifying units that go by the acronym WAYU were inaugurated by the state government to be set up at four locations in Mumbai, a visit to these sites revealed that none of the units were functioning, nobody was monitoring them and there was no unit at Ghatkopar — one of the designated sites

More from this story here.

Earlier this year, Delhi government had installed a device (read the story here, but it is unclear if it was effective and what the next steps are.

And now, architects are floating ideas:

Could a grid of giant filters help clean up Delhi’s polluted air?

Dr. Sarath Guttikunda has previously written about why the anti-pollution devices aren’t a good option:

“Installing an air filter in public is more like avoiding the problem and diverting attention away than solving it. Emissions should always be controlled at the source.

This is not the first time Delhi has experimented with this idea. Before the Commonwealth Games in 2010, an Italian company installed a $300,000-air-filter in Connaught Place, claiming it to be the cleanest spot in Delhi. There are no numbers to back this up, except for the 2.5 kg of dust collected during its one month of operation. Our estimate for Delhi’s particulate matter pollution is approximately 60,000 tons per year, not including seasonal dust storms and agricultural-clearing emissions. That is 5 million kg per month. Assuming that Connaught Place was the cleanest because of the filter’s operations, we would actually have needed at least 2 million of them to cover the city.”

Read the full piece here.

Here’s what he sent us:


Dr. Anumita Roychowdhury, CSE has this to say:

The outdoor purifiers are “a distraction”, says Anumita Roychowdhury, an executive director at the Delhi-based Centre for Science and Environment. “We are saying, focus on the real action of cutting pollution at the source.”

Read the full piece here.

Overall, there are widespread concerns in the scientific community about the effectiveness of such mitigation plans. A project in China focused on an anti-smog tower (listen to its creator), and similar ideas have been proposes elsewhere. However, these ideas have not been found to be successful.


China’s giant smog-sucking tower was simply no match for its air pollution

In China, questions raised over efficacy of smog towers

Here are comments from Dr. Alastair Lewis, University of York (UK) on such programs:

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