At City Air Technologies, we combine living plants with our airflow engineering technology, to provide a plant-based solution to air pollution.

Our bespoke green wall Active Plant Units improve the appearance of existing street architecture & interior spaces, as they make city air healthier in the UK.

Our active living green walls draw in polluted air & pass it through water, thus eradicating particulate matter such as brake dust & tyre wear. The natural microbes in our specially-formulated soil break down the diesel & petrol fumes, while selected pollution-hardy plants replenish oxygen in the returning air. This is green air technology, combined with beautiful plants which support urban biodiversity in the UK.

With minimal maintenance & low-cost leasing contracts, our living green wall Active Plant Units are a cost-effective & elegant way to transform the air we breathe using green air technology.

How Do Active Living Walls Create Green Air Zones?

Active Plant Unit Diagram
  • Work 24/7, 365 days a year due to a combination of the type of hardy herbaceous plants, incorporated lighting & frost-free root zones.


  • Have been university-validated as producing 100 times more clean air than passive plants.


  • Can be designed to be tamper-proof & have concealed security fixings. A unit can be removed & relocated on request.


  • Can match existing street architecture colours & can integrate into existing structures.


  • Can be freestanding on the pavement or retrofitted onto street furniture, schools, hotels & other buildings with high levels of footfall.


Due to the flexibility of our living wall solutions, these can be sited indoors or outdoors, can be active or passive, & can even incorporate other green air technology solutions, such as pre-grown ivy green screens.

How Can Active Living Walls Improve the Air Indoors in the UK?

The average person in the UK spends just 8% of their weekday time outdoors. Indoor air quality can be even worse than outside, due to trapped particulates that have penetrated from outside, lack of ventilation & a different set of chemicals & particulates generated by us indoors. 


Our green air technology is highly effective in this setting, as the same air passes through the plants multiple times.  Living wall APUs can be used in office & retail settings, classrooms, hotel lobbies, leisure spaces & even homes.  Unlike mechanical purification units, the living walls do all the hard work, so there is no need for regular expensive replacement plastic filters (which end up in landfill, creating an environmental problem of their own).


Our active living walls also improve the look of any space, & create biophilic benefits, such as improving mental health & reducing stress.


How Can Active Green Walls Improve Outdoor Spaces in the UK?

Vauxhall Active Plant Unit
  • Green wall APUs can transform the city, creating pockets of purified air where people need them most.


  • They improve atmospheric conditions & biodiversity generally.


  • They are available in various sizes, from compact living walls on a bus shelter (as shown in this photo at Vauxhall station), to huge billboard-sized green walls.


  • Our active & passive living walls can transform the aesthetic of a space without taking up valuable footprint area.


  • We support London’s National Park City movement, & want to show that #VerticalParkland is a critical part of modern urban development in the UK.

What Other Green Air Solutions & Technology Are Available?

In some parts of the UK, other forms of urban landscaping are most appropriate. We offer a range of solutions, from Clean Air Garden planters to Green Screens of pre-grown ivy to act as pollution barriers.  Did you know that ivy green screens have been proven to reduce street level emissions by 40-60%? We are happy to help with community engagement & fundraising for any of our green wall solutions.

An example of the positive impact a green screen can have on air quality in UK schools:

Our Green Screen at Goose Green Primary School has improved playground air quality enormously. Indicative results of nitrogen dioxide (NO2) levels inside the Green Screen in early 2019 show a 48% reduction compared to the level measured in early 2018 (prior to the installation of the Green Screen). Current NO2 levels inside the Green Screen are also 52% lower than the current levels outside the Green Screen (next to the adjacent road). These reductions mean that the whole of Goose Green School’s playground falls within the EU legal limits for NO2.

“Armando was, and continues to be a pleasure to work with. His knowledge of horticulture is amazing and he has shown an excellent understanding of how schools function with his flexible approach to maintenance visits.”

goose green primary school

What Is The Evidence About Active Living Walls?

The study concluded that the active green wall was able to reduce particulate matter in a hotel lobby by up to 73% more than a conventional, passive living wall.

The AEROGATION® system was tested at the 1 Hotel in Miami Beach, where the effects of a passive green wall system were compared with the effects of the AEROGATION® active green wall system in reducing air pollution in a real world situation.

The objective was to independently monitor the effects of the AEROGATION®  active living wall system in improving and remediating indoor air quality in an observed study, and comparing that to other areas without green walls.

1 Hotel Miami Beach: Active Living Wall Experiment Data


To independently monitor the different impact on air quality by equally-sizes areas of standard passive planting & active living green wall technology (phytoremediation).


Measurements taken over a 4-hour period, with 4 data sets taken per hour from each location:

  • Lobby with passive floor planting
  • Active Plant Unit

Active Living Walls' Reduction vs. Passive Planting:

Particulates 10mg/m

VOC mg/m3

Particulates smg/m

Particulates .3mg/m

Carbon Dioxide ppm

Relative Humidity %

Several separate locations in the hotel, including corridors on other upper floors and the main lobby, were measured and compared to the ballroom in real time over a 4 hour period. Results indicated that the active living wall system was able to significantly improve the standards already in place for every measured parameter, when compared to areas that had no interventions. Particulate contaminants at every particle size decreased significantly in comparison to passive planting.

Data collected and analysed shows that the incorporation of an active living wall enabled a significant reduction in a number of indoor air quality measurements to the benefit of the occupants. The system was able to naturally and biologically remediate the air contaminants through biodegradation and physical aqua-filtration whilst maintaining a comfortable physical environment 24 hrs a day.

Is There Evidence From UK Universities About The Impact Of Active Living Walls?

The AEROGATION® system was tested at the Green Wall Centre of Staffordshire University, which carried out a comparative study of the AEROGATION® active green wall system in reducing Nitrogen Dioxide (NO2) air pollution. The study concluded that the green wall APU maintained a consistently high ability to reduce nitrogen dioxide concentration by up to 68.5% in a single pass.

graph showing reduced nitrogen dioxide levels through active living green wall
graph showing reduced nitrogen dioxide levels through active living green wall
graph showing reduced nitrogen dioxide levels through active living green wall

What Does the Data Show About Active Green Walls?