Distribution Characteristics of Indoor PM2.5 Concentration Based on the Water Type and Humidification Method

Abstract

With the industrialization and rapid development of technology that can measure the concentration of pollutants, studies on indoor atmosphere assessment focusing on occupants have been recently conducted. Pollutants that worsen indoor atmosphere include gaseous and particulate matter (PM), and the effects and diffusion characteristics that influence indoor atmosphere vary depending on the indoor and outdoor concentration. White dust is a PM generated from minerals in water used for humidifiers during winter. Therefore, studies on the impact of white dust on human health and its size distribution are being actively conducted. However, since the indoor PM concentration varies depending on the humidification method and water type used, relevant studies are needed. Accordingly, this study examined the change in the PM2.5 concentration and relative humidity on the basis of water types and humidification method. It was found that the indoor PM2.5 concentration varied from 16 to 350 ug/m3, depending on the water types used for an ultrasonic humidifier. Conversely, when using a natural evaporative humidifier, white dust did not increase the indoor PM2.5 concentration, regardless of the mineral content of the water used. Considering both humidification ability and continuous humidifier use indoors, water purifier with nano-trap filters must be utilized for ultrasonic humidifiers.

Exposure at the indoor water–air interface: Fill water constituents and the consequent air emissions from ultrasonic humidifiers: A systematic review

“… Linear regressions on the mass concentrations of airborne constituents from emissions of ultrasonic humidifier and mass concentrations of waterborne constituents. (A) Airborne PM versus aqueous TDS 17 , 18 ; (B) PM versus (Ca + Na + K + Mg), partial mineral content in fill water 17 , 18 , 32 ; (C) PHMG 34 (PHMG indicates polyhexamethyleneguanidine). …”

“…Figure 2A,B indicate that the emitted PM levels in an experimental room or chamber are strongly correlated to waterborne TDS and the major cations of Ca + Na + K + Mg in tap water as humidifier fill water, regardless of the room size and ventilation conditions. The metals Ca + Na + K + Mg were selected as Park et al only reported these metals 32 and similar data were also available for references. 16 , 17 , 18 The p ‐values for the slopes of Figure 2A,B are significant ( p < 0.05), validating the positive, linear relationships between water constituents and airborne PM.…”

“…The mass concentration and size distribution are measured by SMPS or light scattering instruments, and the measured size bins may be different. 32 and similar data were also available for references. [16][17][18] The p-values for the slopes of Figure 2A,B are significant (p < 0.05), validating the positive, linear relationships between water constituents and airborne PM.…”