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.
Highlights
Indoor air quality (IAQ) has been deteriorating due to the high airtightness of buildings and the use of building materials composed of complex chemicals
Equation (1) was considered to be efficient for calculating the exhaust airflow rate to create the calibration concentration by estimating the PM2.5 concentration Ci flowing into the chamber through the filters, concentration of the calibration point Cc, and exhaust airflow rate Qe
This was because the filter utilized in this study was of low cost, usually being installed in vehicles, and low efficiency; the PM2.5 concentration emitted from the filters was constantly maintained at 12–14 μg/m3, which was less than 50 μg/m3 during the experiment
Summary
Indoor air quality (IAQ) has been deteriorating due to the high airtightness of buildings and the use of building materials composed of complex chemicals. The inflow paths of particulate matter (PM) could significantly impact indoor PM concentration, including openings for ventilation and windows that can be recognized by occupants, as well as doors and chinks in the door that are difficult to recognize [4]. Particulate pollutants consist of filterable particulate matter (FPM) and condensable particulate matter (CPM) based on emission characteristics [5]. FPM is generally emitted in solid or liquid form and can be captured by filter [6], whereas CPM is a particulate matter (PM) with a diameter generally less than. FPM and CPM mixed in the outdoor air can increase the indoor PM concentration by infiltration and natural ventilation [8]. The indoor FPM and CPM formed by various factors contribute to the increase in the indoor PM concentration. Public Health 2020, 17, 8638; doi:10.3390/ijerph17228638 www.mdpi.com/journal/ijerph
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