Viewpoints

Are ‘smog-sucking’ solutions solving air pollution?

Smog Free Tower at the World Economic Forum Dalian. Image via www.studioroosegaarde.net
Smog Free Tower at the World Economic Forum Dalian. Image via www.studioroosegaarde.net

Improving air quality is a major issue for cities around the world.

With fossil-fuel based power generation, industrial sources, waste disposal and fossil-fuel based transport the main culprits, according to the European Environment Agency, much of our air, particularly in cities, falls short of levels deemed safe by the World Health Organisation. Indeed, particulate matter (PM 2.5 and 10) is the seventh highest mortality risk in Europe.

Many of the major strategies tackling air pollution encompass taxes and limits, pedestrianising inner cities, investing in public transport or encouraging electric vehicles, but over the last couple of years, more unusual approaches – from smog-sucking towers and engineered moss to anti-pollution paint — have emerged.

But while these solutions are certainly novel, they have attracted much debate as to their role in tackling air pollution. Is it just tinkering at the edges or do they have longevity?

Understanding interventions in a specific urban context

Modena, in northern Italy, is one of a number of cities including Berlin and Brussels, currently testing out the CityTree — an Internet of Things-controlled wall of engineered moss that binds particulate matter and other pollutants, claiming to do the ‘work’ of 275 regular trees.

According to Claudio Carbone, researcher and project manager at Italian National Research Council spin-off Proambiente, who measures the atmospheric pollutants around the City Tree in Modena, these kind of mitigation solutions work best in enclosed spaces.

City Tree is located where the road is narrow, with high traffic, and surrounded by high buildings, causing very stable atmospheric conditions, without effectively mixing air in the canyon and above it.

“We believe City Tree cannot have any effect in open space, because the air volume is too big. But in specific urban environments where dispersion of pollutants is very low, like a canyon, we are trying to understand if it can have an effect in that environment,” he says.

Although the results are not yet in for the Modena City Tree, Carbone says that the added benefit for using City Tree is when there’s just not enough room for regular trees. He adds: “The long-term solutions are all related to the control of emissions, but these mitigation solutions must be adopted in the meanwhile.”

Tackling air pollution must be done at source

Sweden’s Malmo is another city working hard to tackle air pollution. Its city-centre plan focuses on local, staged steps to reduce emissions, particularly from road traffic, its main source of emissions and air pollution.

The city has implemented new bus lanes for public transport, improved public transport, re-built roads and dropped the speed limit from 50 to 40 kilometers per hour so traffic flows more smoothly, and with less congestion. It’s also more difficult for regular passenger cars to drive into the city centre, with commuter parking located outside the city.

Mårten Spanne, an environmental engineer at Malmo’s Department of Urban Development, which conducts air pollution simulations to focus city’s planners, is doubtful that smog-sucking solutions would work for Malmo.

“It sounds crazy. You can’t remove air pollution in an effective way once it’s emitted. You have to reduce the source. It’s the only way to go. Maybe on a theoretical level they can have an impact”, referring to companies putting titanium dioxide in pavements and concrete blocks to reduce nitrogen dioxide levels.

“In an ideal situation, they can reduce the nitrogen dioxide concentration on a heavily polluted street by something like five per cent. You’re fooling yourself if you think you have done something about the problem,” he says.

CityTree in Oslo. Image © Green City Solutions
CityTree in Oslo. Image
© Green City Solutions

Behavioural change

Smog-sucking techniques and vertical air purification solutions can be good for a city, but it’s less about reducing actual pollution, and more about raising awareness, Spanne points out. Behavioural change, commuting by bike, by foot or business collaboration on transport of goods are the interventions that will bring change.

Dutch designer Daan Roosegaarde has risen to prominence globally for his efforts in tackling air pollution in Chinese cities. As part of ‘Smog Free project’, Roosegaarde created a smog-free tower and designed a giant vacuum clear for Beijing as well as plans for an air-purification bicycle.

According to Roosegaarde, stopping air pollution at source is critical, but there also needs to be immediate action. But rather than filling a city with smog-free towers, the aim is to connect infrastructure with greening through plants or trees, as well as government policy.

Smog-free tower has facilitated the interest and dialogue about how to make a city smog-free. “Is one tower the solution for it all? No, of course not, but it is a very, very, very important local solution, and the trigger to make sure that pollution is on the agenda. Instead of just waiting for government to fix it, we want to activate people,” says Roosegaard.

Inspiring action

“Right now, we’re working on a smog-free campaign plan where we can propose a city reduction of CO2, between 10 and 40 per cent, as a collage of different solutions. That is the bigger vision. The tower is very important but only one of these elements,” he says.

Vertical air purification solutions are showing promise to work at a local scale in certain circumstances. Although they receive more hype as novel solutions addressing pollution, they are just one of a range of connected strategies and approaches needed to tackle air pollution. Their role is best seen as a focal point and a way of cutting through to the longer-term agenda. An increased focus moves nearer positive results, keeping the problem of pollution, and the need to cut it at source, at the top of the agenda.

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