Size and mineral composition of airborne particles generated by an ultrasonic humidifier

This study describes the size distribution and concentration of particles expelled by a portable, 3 L ultrasonic humidifier. The ultrasonic humidifier was filled with waters of varying mineral content and hardness. Aerosol size distributions were measured during 8 h of humidifier operation in a typical bedroom. Humidifiers produced approximately 1.22 ×1010 to 2.50 ×1010 airborne particles per milliliter of water consumed, resulting in airborne particle concentrations of 3.01 ‐ 5.91×104 #/cm3, with modes ranging between 109 and 322 nm in diameter. The emission rate of particles varied by water type from 1.02 ×109 to 2.27 ×109 #/s. Lower mineral waters produced fewer, smaller particles when compared to higher mineral waters. Chemical analyses of particles collected with a cascade impactor indicated that the minerals in emitted particles had the same relative mineral concentrations as the fill water. Our results demonstrate that ultrasonic humidifiers should be considered a source of inhalation exposure to minerals dissolved in water, and that the magnitude of exposure to inhalable particles will vary with water quality. This article is protected by copyright. All rights reserved.
Source: Indoor Air - Category: Occupational Health Authors: Tags: Original Article Source Type: research