Abstract

Background: The idea that adverse health effects such as sensory irritation and declining cognitive performance can be caused by exposure to indoor air pollutants is controversial because the occurrence of these symptoms depends largely on a person’s sensitivity and state of mind. Therefore, the relationship between the indoor environment and adverse health effects needed to be explored using both subjective and objective data. In November 2017, two laboratory houses (LH) were built on the campus of Chiba University, Japan, to facilitate a new project called the “Chemiless Town Project Phase 3”. The project was undertaken to investigate the impact of indoor environments on physical and mental health, with the goal of creating healthy indoor environments. The interior and exterior of the two LHs looked the same, but the concentrations of indoor air chemicals were different because the building and interior materials were different.

Method: From 2017 to 2018, 86 healthy volunteers participated in the experiment and evaluated the air quality of the LHs both objectively and subjectively. The objective evaluation methods included measuring brainwaves and heart rate variability. The subjective evaluation methods included asking participants to complete questionnaires while staying in the LH. Simultaneously, indoor air samples were collected from the LHs, and Volatile Organic Compounds (VOC) and aldehydes were analyzed.

Result: The mean concentrations of total VOCs (TVOC) in LHs A and B were 2269 and 76μg/m3, respectively. In the objective evaluation, there was a significant difference in participants’ alpha brainwaves between the two LHs. In the subjective evaluation, there were differences in odor intensity, odor pleasantness, indoor air freshness, participants’ comfort, and how relaxed the participants felt in each of the two LHs.

Conclusion: In this study, it was indicated that TVOC levels and the odor strength could affect human’s quality of life such as indoor comfort and their degree of relaxation through objective and subjective methods.

Keywords: Indoor air quality; Brainwaves; Healthy indoor environment; Heart rate variability; Physical and mental health

Abbreviations: DNPH: 2,4-Dinitrophenylhydrazine; EPM: Environmental Preventive Medicine; GC: Gas Chromatography-Mass; GC-MS: Gas Chromatography-Mass Spectrometry; LH: Laboratory Houses; MVOC: Microbial Volatile Organic Compounds; PC: Personal Computer; QEESI: Quick Environmental Exposure and Sensitivity Inventory; SBS: Sick Building Syndrome; TVOC: Total Concentrations of Volatile Organic Compounds; VOC: Volatile Organic Compounds