INDOOR AIR QUALITY | PLANTS Priority pollutant Plant species tested Dracaena marginata Dracaena Janet Craig Epipremnum aureum Howea forsteriana Schefflera Amate Spathiphyllum Petite Spathiphyllum Sensation The authors found varying removal rates, from 12ppm d-1 (Howea forsteriana) to 27ppm d-1 (Dracaena Janet Craig) 40-88mg m-3 d-1. These rates were maintained in the dark, rose linearly with a concentration increase, but could mostly becontributed to the growing substrate and not the plant. Syngonium podophyllum The study compared plants grown in traditional substrate and hydroculture (no growing substrate) and concluded that indoor plants potted in traditional substrate (1,444 g m-3, rate for 50% benzene removal) possessed a higher removalrate than hydroculture potted plants (739 g m-3, rate for 50% benzene removal) but both treatments removed significant amounts of benzene. Fatsia japonica Ficus benjamina Comparison of the above-ground plant parts and the root zone to remove formaldehyde in the day and night. Fatsia japonica removed formaldehyde faster than ficus benjamina (50% decay in 96 and 123 minutes respectively). Both plants removed formaldehyde in a 1:1 ratio (above-ground parts: root zone) in the day, and 1:11 at night. The root zone was found to remove formaldehyde primarily through the microorganisms and roots (90%) and asmallamount through growing medium absorption (10%). Formaldehyde Chlorphytum comosum Aloe vera Epipremnum aureum All plant-substrate systems removed formaldehyde, with chlorphytum comosum the most effective.The authors also determined that microorganisms in the substrate accounted for approximately 50% oftheformaldehyde removal in all the plantsubstrate systems. PM2.5 Chlorophytum orchidastrum Ficus lyrata Nematanthus glabra Nephrolepis cordifolia duffii Nephrolepis exaltata bostoniensis Schefflera amate Schefflera arboricola Investigated the single pass removal efficiency (SPRE) of plants in an active green wall for PM2.5 removal. The authors found that all studied plants removed PM, with fern species recording the highest efficiencies. Nephrolepis exaltata bostoniensis removed the most PM2.5 with a SPRE of > 70%. Benzene Benzene Nephrolepis exaltata bostoniensis or Boston Fern removed the most PM2.5 of plants studied substrate may influence removal as measured with VOCs. RH literature has produced conflicting results. Anecdotally, plants would be expected to increase RH indoors, but this is not always the case. We suggest a standard method be devised controlling chamber/room size and ventilation rate to facilitate effective comparison between different plant species. We believe plants should not be considered as a single entity, expected to provide all the above described benefits. There is large performance variability between species, so we recommend consulting literature to ascertain their suitability for a given benefit. Although some benefits of indoor plants are less clear, when considered as a whole with all the benefits combined we believeplants should be considered as a building service, alongside traditional ventilation systems. For a full list of references, see this article at www.cibsejournal.com or read the full paper at www.cibse.org.uk/symposium CJ CURTIS GUBB and CHRISTIAN PFRANG, Department of Earth, Geography and Environmental Science, University of Birmingham CXG857@student.bham.ac.uk Result Formaldehyde TIJANA BLANUSA and ALISTAIR GRIFFITHS, Science Department, Royal Horticultural Society Table 2: Selected studies showing plants removing 2019s priority pollutants benzene and formaldehyde Raising the light level to 22,000lux made achievable with supplementary LED lighting increased the CO2 removal 50-fold in some species 14 June 2019 www.cibsejournal.com CIBSE Jun19 pp11-14 Green plants Supp.indd 14 24/05/2019 15:11