Cork should scrap 'robot trees' if air quality claims cannot be verified, says expert

The project was one of more than 500 in 11 counties funded as part of a €55m National Transport Authority stimulus package in response to the pandemic.

Designed to filter the air and absorb the toxic pollutant called particulate matter from the air by moss filters, they also have in-built sensors used to collate air quality data for analysis.

PM2.5, known as particulate matter, is all solid and liquid particles suspended in air, such as dust, pollen, soot, smoke, and liquid droplets. 

Since the introduction of the robot trees, they have been criticised by environmental activists and scientists alike.

University College Cork (UCC) emeritus professor of chemistry, John Sodeau, was one of those who criticised their introduction as a waste of funds.

One of Europe’s leading experts on air quality and a founder of the Centre of Research into Atmospheric Chemistry at UCC, Prof Sodeau has now said that it is time for the claims made about their health benefits to be verified once and for all, or they should be removed.

He said that the earliest claims by Cork City Council indicated that they would also remove nitrogen dioxide gas from vehicle exhausts.

However, earlier this year, Cork City Council confirmed that they are not designed to tackle nitrogen dioxide.

Prof Sodeau said the other claims made by the manufacturers now needed to be stood up or Cork City Council should follow London’s lead and remove them —ironically because all the moss had been destroyed by local air pollution.

“Green City Solutions, who created the devices, said they had commissioned an independent scientific study by the Leibniz Institute for Tropospheric Research (TROPOS), which stated that a filter effect of 53% was detectable at a distance of 1m from the tree, with an effect of up to 82% directly at the moss.

“The report is briefly referred to in an actual TROPOS publication, which tells a somewhat different story. 

"Here, it only says that a reduction of up to 30% for the particles is found for indoor measurements. 

"No figures for outside filtering is given other than, as expected, ‘the measurements were shown to be dependent on meteorological conditions’.

"The only way for Cork City Council to assess whether or not they have wasted a very large amount of taxpayers’ money is to confirm these measurements,” he said.

Data has still not been published on their efficacy despite being expected on repeated occasions, he added.

Green City Solutions says the performance of the trees “were evaluated in extensive scientific measurement”.

Fianna Fáil councillor Colm Kelleher, who during his term as lord mayor officially unveiled the devices, said it was time to pull the plug on them. 

“In the absence of any data to show if these things are doing any good, I think it’s time to just plug them out. 

"At least we’ll save something on the cost of electricity alone,” he said.

Earlier this month, councillors were told the analysis of the data is ongoing.