Abstract
The study investigates the influence of indoor plants on relative humidity (RH) and the subsequent reduction in particulate matter (PM) in a naturally ventilated office room at CSIR- NPL, Delhi. PM concentrations were compared under two conditions: control (without plants) and experimental (with eight potted Epipremnum aureum plants). The comparison was conducted under two distinct cases: background PM, and induced PM from incense burning.
The presence of plants resulted in an average RH increase of 13.55% and a temperature decrease of 4.1%. Plant-induced RH elevation led to a sixfold reduction in PM I/O ratios. RH values (>60%) were negatively correlated with ultrafine, fine, and coarse particles. Plant-induced RH accelerates the deposition loss rate of all sized particles by ∼44% and reduces the infiltration rate by ∼78%. During pre-emission, in addition to PM dry deposition, plant-induced RH contributed to a substantial reduction of fine PM by 6.53% and coarse PM by 26.45% respectively. During incense burning, in the presence of plants, ultrafine PM concentrations dropped by 23.41%, fine PM by 72.39%, and coarse PM by 71.49%. It demonstrates that PM chemical composition significantly influences PM reduction, as it alters particle hygroscopicity. There was a decrease in the mass percentage of elements like Na, Mg, Al, Si, Cl, and K by 1.87, 1.23, 2.26, 5.48, 0.66, and 0.91 percent respectively. It can be inferred that to achieve a 13% increase in the average RH, plants with a leaf area size equivalent to ∼6% of the room surface would be required.
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•At RH>60%, negative correlations with different-sized PM observed•Indoor plants-induced RH reduced the I/O ratio of PM concentration by 6-times•Indoor plant-induced RH observed to increase PM deposition loss rate•Maintaining RH ≥60% should be the criteria for selection of number of plants required in a room•To improve RH by 13%, plants with leaf area equivalent to only 6% of room surface is required