London, UK
Thomson Reuters Foundation

Londoners will be able to see how dirty the British capital's air is through a public art installation launched on Tuesday, as pressure mounts to tackle the hidden killer.

Large air balloons, which change colour to show how much harmful nitrogen dioxide has been measured in the air at sites across the capital, have been installed in central London for the project led by environmental charity Hubbub.

London Hubbub installation

A woman stands in front of the "Pollution Pavilion" art installation which visualises levels of air pollution in London, United Kingdom, in an undated handout photograph provided by the Hubbub environmental charity. PICTURE: Hubbub via Thomson Reuters Foundation

"Air pollution is largely an invisible issue...and that makes it very difficult for people to understand," Gavin Ellis, co-founder of Hubbub, told the Thomson Reuters Foundation.

"The installation stops people in their tracks. It's quite attention grabbing: it's bright, it's a little bit different, and whether people are interested in air pollution or not, I think it's going to make them stop and take notice."

Many of the world's cities, which the United Nations says account for about three-quarters of planet-warming emissions, are getting behind global climate goals and green innovations, from electric buses to pollution-sucking urban gardens.

Air pollution is linked to asthma and cancer and kills 800 people every hour globally. It kills more than three times as many people a year than malaria, tuberculosis and AIDS combined

More than 80 per cent of Britons are worried about the how pollution could affect them or their families, rising to 92 per cent of parents with a child aged under five, according to a survey of 3,000 people carried out for Hubbub. 

Like many major cities, London's toxic air is largely caused by emissions from petrol and diesel vehicles. Official data found two million Londoners lived in areas with illegally high levels of air pollution last year. 

The interactive "pollution pavilion" art installation has buttons which passers-by can press to compare data on annual air quality data gathered at five monitoring stations.

The balloons change colour from light blue for the cleanest areas to deepening pink for readings above legal limits for toxic nitrogen dioxide.

The project was created by Hubbub together with partners including the "Climate and Cities" artist collective and researchers at King's College London who provided the air pollution data.

London mayor Sadiq Khan hailed the installation as an example of "creative ways to help the public understand the dangers of air pollution, and encourage them to take action".

Another campaign group last year installed billboards to alert Londoners to levels of air pollution in areas including some of the city's most exclusive enclaves.