The Horticulture Journal 89 (3): 319–327. 2020. e Japanese Society for doi: 10.2503/hortj.UTD-110 JSHS Horticultural Science http://www.jshs.jp/ Higher Attention Capacity After Improving Indoor Air Quality by Indoor Plant Placement in Elementary School Classrooms Ho-Hyun Kim1, In-Young Yeo2 and Jae-Young Lee3* 1Department of Information, Communication and Technology Convergence, ICT Environment Convergence, Pyeongtaek University, Pyeongtaek, 17869, Korea 2Department of Environmental Radiation & Radioactivity Assessment, Korea Institute of Nuclear Safety, Daejeon, 34142, Korea 3Institute of Life Science & Resources, Kyung Hee University, Yongin, 17104, Korea This research evaluated the attention capacity of 70 pupils in the sixth grade with the intervention of indoor air quality regulated by indoor plant placement in the classrooms of two elementary schools in Seoul, South Korea. Two sets of three-week measurements were conducted with an interval of 12 weeks from 27th June to 7th October, 2016. We divided subjects into two groups (Group I and II): subjects in Group I occupied classrooms without indoor plants and those in Group II occupied classrooms with indoor plants. The classrooms with indoor plants had indoor levels with constant air temperature (approximately 26°C), relative −3 humidity (around 50%), and carbon dioxide (CO2) (around 1100 mg·m ). Additionally, 12-week placement of indoor plants reduced the indoor concentrations of airborne contaminants. After 12 weeks of the experiments, the subjects’ attention capacity improved as demonstrated by a standard questionnaire (Frankfurt Aufmerksamkeits-Invertar, FAIR). Indoor plant placement showed little difference in terms of efficiency (FAIR-E) and continuity (FAIR-C) scores, but exhibited a significant improvement for performance (FAIR-P) (increasing from 0.964 to 0.989) and quality (FAIR-Q) scores (increasing from 0.945 to 0.973). Based on multiple regression, the current study suggested that indoor plant placement was one of the most important factors to improve the attention capacity of pupils in classrooms. Key Words: airborne contaminant, FAIR (Frankfurt Aufmerksamkeits-Invertar), indoor environment, indoor occupant, volatile organic compound (VOC). quent mechanical ventilation. However, the ventilation Introduction tends to be done without considering the contamination Spending more of our lives indoors is one of the most level in indoor spaces (Moya et al., 2018). Researchers widespread current trends. Earlier studies reported that have suggested that indoor plant placement could be an the general public nowadays spend approximately 80% alternative method for regulating indoor environments of their daily lives indoors (Orwell et al., 2004; United efficiently with the expectation of physical, as well as States Department of Labor, 2006; WHO, 2010). Con‐ psychological benefits (Adachi et al., 2000; sequently, it could be postulated that the health of in‐ Bringslimark et al., 2009; Dijkstra et al., 2008; Lohr door occupants is more greatly influenced by the indoor et al., 1996; Orwell et al., 2006; Wood et al., 2002). In environment quality than outdoor factors. addition to the visual attractiveness, indoor plant place‐ Indoor occupants have often tried to maintain their ment provides additional benefits to indoor environ‐ indoor environments at a comfortable level using fre‐ ments via plants’ metabolic actions (Bringslimark et al., 2009; Gary and Birrell, 2014; Ottele, 2011; Raanaas Received; June 9, 2019. Accepted; October 31, 2019. et al., 2011; Wolverton, 1997). First Published Online in J-STAGE on December 28, 2019. That is, the placement of indoor plants regulates air This work was carried out with the support of “Cooperative Research temperature and humidity through evapotranspiration Program for Agriculture Science and Technology Development (Davis and Hirmer, 2015; Mangone and van der (Project No. PJ014270032019)” by the Rural Development Administration, Republic of Korea. Linden, 2014; Perez-Urrestarazu et al., 2016). After the * Corresponding author (E-mail: [email protected]). National Aeronautics and Space Administration © 2020 The Japanese Society for Horticultural Science (JSHS), All rights reserved. 320 H.-H. Kim, I.-Y. Yeo and J.-Y. Lee (NASA) Clean Air Study presented a study about the and measuring the indoor environment. Detailed de‐ metabolic actions of plants to remove toxic agents from scriptions of the current study were as follows. the air in the 1980s (Wolverton et al., 1984, 1989), re‐ searchers have reported similar results that indoor plant Arrangement of facilities and subjects placement helped reduce the indoor level of airborne The current study used two groups of classrooms contaminants (Kim et al., 2011; Lim et al., 2009; (Group I and II) at two elementary schools (Schools A Orwell et al., 2006; Wood et al., 2002). and B) which were established in 2011. Each school The health of indoor occupants is greatly influenced provided two classrooms: one classroom without indoor by the indoor environment quality and the accumulation plants (Group I) and the other classroom with indoor of carbon dioxide (CO2) (Shendell et al., 2004) and plant placement (Group II). The classrooms of both volatile organic compounds (VOCs) (Daisey et al., schools had two opposing walls with windows. The 2003; De Kluizenaar et al., 2016) are caused by insuffi‐ classrooms of both schools had the same rectangular cient ventilation. Based on previous studies, it is postu‐ dimensions of 9.0 m long and 7.7 m wide. To regulate lated that the indoor environment quality plays an the indoor environment at an air temperature of 26°C, important role in the health and work performance of individual systems of mechanical ventilation and air indoor occupants (Al Horr et al., 2016; Blueyssen et al., conditioning were used for two hours twice a day 2016; Frontczak et al., 2012; Kosonea and Tan, 2004; (from 10:00 a.m. to 12:00 p.m. and from 2:00 p.m. to Raanaas et al., 2011; Wyon, 2004). Other reports also 4:00 p.m.). pointed out that the interaction between indoor occu‐ We recruited 70 pupils in the sixth grade of elemen‐ pants and plants in indoor environments can alter the at‐ tary school who could attend school for the experimen‐ titudes, behavior, and physical responses of the indoor tal duration without absence. All the pupils participated occupants, improving their productivity and overall sat‐ in this experiment with the permission of their parents isfaction (Gary and Birrell, 2014; Lohr et al., 1996; after fully understanding the experimental procedure. Relf, 1990; Shoemaker et al., 1992). We enrolled 40 participants for each of two classrooms Young individuals in their growth phase are highly at School A and 30 participants for each of two class‐ sensitive to environmental factors (Faustman et al., rooms at School B, respectively (Table 1). 2000). They usually spend more than half of their daily lives in classrooms. Classrooms can be distinguished Indoor plant placement from other indoor environments by their overpopulation The current study followed the descriptions of certain and abundant pollution sources (Becker et al., 2007; previous reports regarding the types, quantity and meth‐ Fromme et al., 2008; Theodosiou and Ordoumpozanis, ods for indoor plant placement (Kil et al., 2008; 2008). Some researchers suggested that exposure to a Soreanu et al., 2013; WHO, 1986). We placed indoor cleaner natural environment could help people improve plants in the classrooms of Group II at both schools for attention capacity (Felsten, 2009; Kaplan, 1995; 12 weeks (from 6th March to 28th May) to acclimatize Tennessen and Cimprich, 1995; Wells, 2000). Others the pot plants to the indoor environment and removed also proposed that proper management of the indoor en‐ them for four weeks to reduce any environmental dam‐ vironment quality using plants could enhance the atten‐ age to them prior to the actual examination. Then, in‐ tion capacity of indoor occupants (Momovic et al., door plants were again placed in the classrooms for the 2009; Raanaas et al., 2011). entire experimental duration (12 + 3 weeks, 27th June Considering the points above, the current study tried to 7th October). to clarify the relationship between the attention capacity We classified pot plants into two categories (large of indoor occupants and their indoor environment quali‐ and small) based on a previous report by Lee and Kim ty when regulated by indoor plant placement. The aim (2005): a large pot plant was one with a leaf area of of this study is to propose an appropriate indoor envi‐ 3000 to 5000 cm2 and a small pot plant was one with a ronment quality for elementary school pupils during leaf area of less than 1000 cm2. Considering capacity their time indoors to improve attention capacity. for formaldehyde decomposition, earlier researchers recommended the suitable pot plants: lady palm, rubber Materials and Methods plant, areca palm, and heavenly bamboo as large plants This research evaluated the attention capacity of 70 and bird’s-nest fern, peace lily, golden pothos, and tiny pupils in the sixth grade with the intervention of indoor ardisia as small plants (Kil et al., 2008; Kim et al., air quality regulated by indoor plant placement in the 2009; Lee and Kim, 2005). A large pot plant was grown classrooms of two elementary schools in Seoul, South in a pot with a size of ø30 cm × 41 cm (h) (28.976 L) or Korea. Two sets of three-week measurements were con‐ ø24 cm × 23.5 cm (h) (10.626 L), and a small plant was ducted with an interval of 12 weeks from June 27 to grown in a pot with a size of ø18 cm × 15 cm (h) October 7, 2016. The authors followed the same pat‐ (3.815 L). Then, the researchers placed more than one terns as previous reports by Kim et al. (2013, 2016) in large pot plant and one small pot plant in an area of arranging facilities and subjects, placing indoor plants, 6 m2 by the window wall of each classroom, following Hort.