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  • Author or Editor: Young-Wook Lim x
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A cohort of sixth grade students at two newly constructed elementary schools in Seoul, South Korea, performed a self-assessment of ocular discomfort symptoms in association with indoor air quality (IAQ) by indoor plant intervention from early June to mid-Oct. 2011. Indoor plant intervention made little difference in air temperature and relative humidity, but stabilized the increasing levels of carbon dioxide. The indoor concentrations of formaldehyde and ethylbenzene showed little difference, but those of toluene and xylene showed a decreasing trend in classrooms with indoor plants. The participants in classrooms without indoor plants exhibited an increase in ocular discomfort symptoms at School A and a decrease in symptoms at School B; those in classrooms with indoor plants demonstrated a decrease in frequency at both schools. The variation of symptom severity did not follow a clear trend. Participants assessed their symptom severity of ocular discomfort with four options from three points for frequent occurrence to zero points for no occurrence. Among participants in classrooms without indoor plants, symptom severity significantly worsened at both schools as the scores increased from 1.96 to 2.17 at School A and from 2.27 to 2.34 at School B; among those in classrooms with indoor plants, symptom severity significantly lessened at School A and slightly worsened at School B as the scores decreased from 2.33 to 1.98 at School A and increased from 2.35 to 2.42 at School B. After spending the experimental duration in classrooms without indoor plants at both schools, 34.8% of participants at School A and 33.3% of participants at School B perceived their symptom severity as having increased. At Schools A and B, indoor plants decreased the frequency of participants experiencing an increase of symptom severity by 13.0% and 9.7%, and increased the frequency of participants reporting decrease of symptom severity by 34.8% and 22.6%.

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The efficiency of volatile formaldehyde removal was assessed in 86 species of plants representing five general classes (ferns, woody foliage plants, herbaceous foliage plants, Korean native plants, and herbs). Phytoremediation potential was assessed by exposing the plants to gaseous formaldehyde (2.0 μL·L−1) in airtight chambers (1.0 m3) constructed of inert materials and measuring the rate of removal. Osmunda japonica, Selaginella tamariscina, Davallia mariesii, Polypodium formosanum, Psidium guajava, Lavandula spp., Pteris dispar, Pteris multifida, and Pelargonium spp. were the most effective species tested, removing more than 1.87 μg·m−3·cm−2 over 5 h. Ferns had the highest formaldehyde removal efficiency of the classes of plants tested with O. japonica the most effective of the 86 species (i.e., 6.64 μg·m−3·cm−2 leaf area over 5 h). The most effective species in individual classes were: ferns—Osmunda japonica, Selaginella tamariscina, and Davallia mariesii; woody foliage plants—Psidium guajava, Rhapis excels, and Zamia pumila; herbaceous foliage plants—Chlorophytum bichetii, Dieffenbachia ‘Marianne’, Tillandsia cyanea, and Anthurium andraeanum; Korean native plants—Nandina domestica; and herbs—Lavandula spp., Pelargonium spp., and Rosmarinus officinalis. The species were separated into three general groups based on their formaldehyde removal efficiency: excellent (greater than 1.2 μg·m−3 formaldehyde per cm2 of leaf area over 5 h), intermediate (1.2 or less to 0.6), and poor (less than 0.6). Species classified as excellent are considered viable phytoremediation candidates for homes and offices where volatile formaldehyde is a concern.

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