The Role of Indoor Plants in air Purification and Human Health in the Context of COVID-19 Pandemic: A Proposal for a Novel Line of Inquiry

Phytoremediation of formaldehyde by three selected non-native indoor plant species

Formaldehyde is an organic volatile compound and a commonly used chemical in various construction materials thus causing dwellers to be exposed to it inside a building. Its remediation from indoor air has been carried out through various techniques where potted plants and living walls are at the front foot. It is necessary to study plants under various conditions for their efficiency. We selected three plant species Epipremnum aureum, Chlorophytum comosum, and Spathiphyllum wallisii non-native of Bahrain. These plants were tested under normal conditions in a sealed fumigation box where formaldehyde concentration was kept ∼3 ppm, CO2 ∼ 450 ppm, light intensity 1000 Lx (equal to 13.5 µmol.m-2.s-1), irrigated with tap water. Analysis of Variance (ANOVA) statistical method was performed to test the significant differences of purification efficiencies of the tested indoor plants against HCHO. In addition, the statistical method was used to test the significant difference, if any, of the plants to CO2 emission because of absorbing HCHO. The physical health of plants and their short-term remediation ability reveals that all plants exhibited up to 70% remediation potential and tolerance to remediate the target chemical. It is evident that the impact of local environmental factors on the plants is negligible.

Submerged leaves of live indoor foliage plants adsorb H1N1 influenza virus from suspension

Control of hazardous indoor particles using plants has attracted interest due to the increasing worldwide air pollution and spread of pandemic-causing viruses. However, the interaction between human pathogenic viruses (HPVs) and live plants has not been examined largely due to issues in detecting tiny amounts of infectious viruses in a carrier (such as an aerosol) and the lack of suitable examination methods. In this study, as a novel evaluation method, the effect of submerged leaves of live plants on HPVs in water was examined, using the H1N1 influenza virus as a model. Selected plant foliage of a live plant was immersed in a small bag containing HPV water suspension. In an initial screening test, the activities of 20 different plant species on the virus suspension were evaluated using a rapid virus detection kit. Ten plant species had the capability to decrease virus concentrations in the water suspension within 72 h. Among the experimental plant species, Epipremnum aureum showed the highest virus decreasing characteristics when examined using both the kit and quantitative real time polymerase chain reaction. The capacity of immersed leaf of live E. aureum to decrease viral content was enhanced when the plant-containing pot was electrically grounded to the earth (approximately 70% decrease in virus concentration). The foliage sample analysis showed that virus adsorption to the plant foliage surface could be the major reason for the decrease in the suspension. These results suggest that the proposed method can be applied to select plants to further investigate plant-HPV interactions.

Towards the new generation of courtyard buildings as a healthy living concept for post-pandemic era

COVID-19 has laid a context for holistic research and practical approaches towards health issues in buildings. This study focuses on one particular residential building type, which is a combination of a modern apartment building with private double-oriented terraces, and a traditional courtyard building. This principle improves several aspects of healthy buildings and contributes to address indoor-outdoor interactions, daylighting, and the use of natural ventilation. The purpose of this study is to determine the factors underlying a particular type of semi-outdoor space within building forms and to explain their microclimatic behavior in buildings. One solid model and twelve porous apartment buildings with different numbers of porous sides, and terrace widths are evaluated using computational fluid dynamics. The k-ε turbulence model is adapted to simulate airflow in and around a four-story building. CFD simulations were validated against the wind-tunnel measurements. Investigations indicated that increasing the number of porous sides reduces the internal mean and maximum ages of air by -15.75 and -36.84%, which means improved ventilation performance. However, it leaves a negative trace on ventilation of the semi-outdoor spaces. Meanwhile, increasing the width of the terraces enhances the ventilation performance by reducing the mean age of air in units, courtyards, and terraces by -20%, -20%, and -9%, respectively.