Smart air filters with moss lower pollution on London streets

air filters pollution particles

Photo: Green City Solutions


January 15, 2020







January 15, 2020






The Waltham Forest borough in the northeast of the United Kingdom’s capital city has installed three devices in the open to purify the air of suspended particles including PM1, PM2.5 and PM10. The smart air filters project was done in cooperation with green technology firms Evergen Systems Ltd. and Green City Solutions GmbH. The system equipped with internet of things or IoT contains moss.

Following a number of trials and temporary deployments, this is the first known permanent setting. The CityTree has a bench, a green wall, tools to measure the performance and environmental data, solar panels and a battery to power the automatic irrigation system. The air filters have the capacity equivalent to as much as seven thousand people to breathe freely, the German company said.

The local authorities chose two places with chronical pollution in Leytonstone: the tube station and the main street. Moss has a large surface, enabling strong absorption and evaporation for cooling.

The smart walls are some four meters high and three meters wide. Engineers and decision makers in the cities around the planet have been long analyzing how prototypes fit in what is usually a limited street space where they are required.

Several CityTree air filters were placed for a while in London’s Piccadilly Circus, in Newcastle, Berlin, Oslo, Paris, Drammen in Norway, Amsterdam, Brussels and Hong Kong. The tryouts revealed some weaknesses in the climate infrastructure solutions, mostly due to an exceptionally hot and lengthy summer two years ago, prompting a design overhaul.

Researchers from Green City were also looking into the possibility of mounting the purifying tower onto trucks for demonstrators or moving groups as well as for construction sites.

The green wall can bind over 80% of fine dust in certain cases, according to some of the measurements

A tufting plant called biting stonecrop or wallpepper, sedum acre, is used for the protective layer on the moss, project documents showed. The green wall can bind more than 80% of the said fine dust in certain cases, according to some of the measurements.

The manufacturers claim one CityTree is equivalent to 275 trees. The calculations revealed the air filters take out a maximum of 240 tons of carbon dioxide per annum, but that they also save citizens from nitrogen dioxide.

Waltham Forest has been active in the battle against pollution and can already boast of partial progress. It declared a climate emergency in April and started the procedure for the establishment of a specialized commission.

The municipal officials are working on the measures to face the issue relevant for the whole world and they say they would increase the pressure on the government and relevant institutions on an intermediate level.

The suitability of prototypes is being analyzed across the planet as they must fit in what is usually a limited space in the street where they are needed

Beijing managed with its persistent measures to halve PM2.5 particle pollution in six years.

In our region, we can point to the example of Bulgaria’s capital Sofia, where the protocol is being upgraded for the response in cases of forecasts of excessive levels of harmful dust. Air pollution triggers inspections and the opening of buffer parking spaces. Drivers can leave cars for free outside several subway stations if they have tickets for public transport.

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