Indoor air concentrations of carbon dioxide (CO2), nitrogen dioxide (NO2), and ozone (O3) in multiple healthcare facilities

Abstract

This study evaluates indoor air concentrations of CO2, NO2, and O3 and their relationship to other indoor environmental factors in facilities with occupants susceptible to air contaminants, such as hospitals, senior specialized hospitals, elderly care facilities, and postnatal care centers. Indoor air samples were collected from 82 indoor facilities in South Korea and organized by region. Spearman’s correlation and Kruskal–Wallis analyses were employed to examine the relationship among and differences between contaminants in the indoor facilities and indoor/outdoor differences of NO2 and O3 concentrations. Significant correlations were found between CO2 and NO2 concentrations (r2\u2009=\u20090.176, p\u2009<\u20090.01), as well as NO2 and O3 concentrations (r2\u2009=\u2009−\u20090.289, p\u2009<\u20090.0001). The indoor/outdoor concentration ratios in the indoor facilities were 0.73 for NO2 and 0.25 for O3. CO2 and NO2 displayed the highest mean concentrations during spring, while O3 displayed the highest and lowest mean concentrations during fall and summer, respectively. The calculated hazard quotient (HQ) for NO2 was higher than the acceptable level of 1 in postnatal care centers, thus posing a health risk for children. Study results indicate that efficient ventilation is required to reduce indoor contaminants in multiple healthcare facilities. This study provides a novel approach toward health risk assessment for indoor facilities with susceptible occupants on a large geographical scale.