Effectiveness of indoor plants for passive removal of indoor ozone

Indoor vegetation is often proposed as a passive approach for improving indoor air quality. While studies of outdoor environments indicate that vegetation can be an important sink of outdoor ozone, there is scant data in the literature concerning the dynamics of ozone uptake by indoor plants. This study determined ozone deposition velocities (v_d) for five common indoor plants (Peace Lily, Ficus, Calathia, Dieffenbachia, Golden Pothos). The transient v_d was calculated, using measured leaf areas for each plant, for exposures mimicking three diurnal cycles where ozone concentrations in chamber tests were elevated for 8 h followed by 16 h in the absence of ozone. Estimates of v_d at the end of the first exposures ranged from 5.6 m h⁻¹ for Golden Pothos to 0.9 m h⁻¹ for Peace Lily. Values of v_d were approximately 50% and 66% lower at the end of a second exposure and third exposure, respectively. Estimates of v_d were also made for a range of photosynthetic active radiation (PAR) levels typically observed indoors. An increase in PAR from 0.6 to 41.2 μmol m⁻² sec⁻¹ resulted in increases in v_d ranging from a factor of 1.7 (Diffenbachia) to 4.7 (Peace Lily). For deposition velocities measured in this study, the ozone removal effectiveness ranges from 0.9% to 9% for leaf surface area to room volume ratio of 0.06 m⁻¹ (approximately one plant for every 1.8 m² of floor area) when accounting for values of air exchange and background loss typical of a residential environment.