FEASIBILITY STUDY ON MENTAL HEALTHCARE EFFECT USING PLANTS INSTALLATION IN OFFICE SPACE

 According to a survey by the Ministry of Health, Labor and Welfare, the number of mood disorders tends to increase year by year in Japan. Under such a background, from December 2015, it is obliged for employers to perform stress checks of workers once a year. In such a stress society, improvement of office environment is an urgent issue. As is well known, some foliage plants have effects of humidity control and VOC removal from indoor air, improvement of productivity and reducing workers' mental stress as well.<br> In the past, a number of previous studies on indoor plants focusing on these effects have been seen, and most of them were implemented in simulated office spaces in the past. However, recently Iwasaki et al. and Matsumoto et al. have installed some plants in actual office spaces and the psychological effects of plants on office workers are beginning to be considered.<br> The objective of this study is to examine the effect of indoor plants on physiological/psychological responses and productivity, and to demonstrate the mental healthcare for office workers. In order to clarify the effect of indoor plants, we conducted a demonstration experiment in an office. This experiment aims to clarify the effects of indoor plants arranged in workplaces on workers' mental health, such as physiological responses, psychological responses and productivity.<br> The experiment was performed in two rooms (Office A, Office B) in an office on the eighth floor of a building located in Kyoto, Japan. Office A was a call center and Office B was a general office. Subjects were office workers working in one of the above two rooms. Twenty-two healthy people in Office A and 19 healthy people in Office B participated in the experiment. Participants were required to measure physiological responses and answer a Web questionnaire after work once or twice a week. Each office worker worked as usual during the experiment period.<br> The experiment was performed from the end of March 2016 to the beginning of September 2016. In the experiment, nine cycles (one cycle is two weeks) were conducted while changing the type of plants. Plants were arranged in the same amount as possible with a green cover ratio of 10 %. A preliminary experiment without plants was conducted as a reference case. Survey items are divided into four items: indoor environment (temperature, humidity, CO₂ concentration, illuminance, sound level), physiological responses (salivary amylase activity, critical flicker fusion frequency (CFF)), psychological responses (a questionnaire survey through the Web based on SAP and a questionnaire survey “Jikaku-sho shirabe” by which evaluated work-related fatigue feelings and fatigue symptom intensity), and productivity (simple task, calls per hour (CPH)).<br> Indoor environment indices of this study ranged wider than those of the laboratory experiment. The result of evaluating the thermal comfort of each office using PMV showed that Office A was slightly warm, while Office B was neutral. The relaxation effects of plants on visual fatigue were found to be significant in CFF for female when arranging the plants with some petals. Mean score of fatigue symptom intensity showed that foliage plants have a significant effect to reduce the feelings of drowsiness. Effect of the improvement of the productivity using plants installation could not be confirmed in terms of simple task and CPH. Our results suggested that plants installation in office space has some mental healthcare effects, although this study had some limitations because of the demonstration experiment. Some experimental problems related with plants preparation restriction, plants order, a variation of some indoor environment indices, LED lamp lightings are to be solved in the future.