A Spanish study has demonstrated the effectiveness of active vertical gardens, also known as green walls, in improving air quality inside buildings and enclosed spaces.
Researchers at the University of Seville explained that vertical gardens represent a natural alternative to industrial air purification systems, with lower energy consumption and a positive environmental impact. The results were published Monday in the journal Atmospheric Environment.
Vertical gardens are an innovative agricultural technology based on growing plants vertically on building facades or internal and external walls, instead of traditional cultivation in soil. These plants are installed within specialized support systems that include moisture insulation layers, alternative growth media, and integrated automated irrigation and nutrition systems.
These gardens aim to exploit limited urban spaces to enhance vegetation cover, which contributes to purifying the air from pollutants, lowering building temperatures, and reducing noise, while adding an aesthetic and psychologically soothing touch to the urban environment.
The researchers conducted their experiments inside a closed glass chamber to measure the ability of different plant species to reduce pollutant concentrations, amid growing global concern regarding indoor air pollution and its impact on public health.
The team noted that indoor air pollution represents a serious health problem in many countries, as it is linked to "Sick Building Syndrome", which negatively affects individual comfort and productivity, as well as students' ability to learn.
The study showed that sources of indoor pollution include paint solvents, perfumes and cosmetics, building materials, furniture, and tobacco smoke, along with daily activities such as cooking, heating, and cleaning, as well as the infiltration of outdoor pollutants such as urban dust.
The researchers relied on testing 5 plant species within an "active green wall" system, which are Spathiphyllum, Tradescantia zebrina, Philodendron scandens, Ficus pumila, and Chlorophytum comosum.
During the experiments, gaseous pollutants such as nitrogen dioxide and sulfur dioxide were introduced, in addition to volatile organic compounds (VOCs) such as formaldehyde, acetone, hexane, and heptane, and the changes in their concentrations inside the chamber were then monitored.
The results recorded a significant decrease in pollutant levels, especially formaldehyde and sulfur dioxide; the total removal rate ranged between 96 and 98 percent after 24 hours for all plant species. The results also showed that purification efficiency was highest for formaldehyde and nitrogen dioxide.
In a relatively short time, specifically just 15 minutes after the introduction of volatile organic compounds, their concentration decreased by a rate ranging between 24 and 40 percent across all plants, which indicates the rapid response of these systems, according to the team.
The findings indicated that the use of vertical gardens inside buildings can be an effective and sustainable solution for improving indoor air quality, thereby enhancing individual health and limiting the risks associated with pollution in closed environments.
