Measurements of particle size distributions produced by humidifiers operating in high humidity storage environments

Hung, Duong Van; Tong, Shengnan; Nakano, Yusuke; Tanaka, Fumihiko; Hamanaka, Daisuke; Uchino, Toshitaka

doi:10.1016/j.biosystemseng.2010.07.001

Cited by 27 publications

(14 citation statements)

References 15 publications

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“…The mass concentration of particles generated by the humidifier with RO water was below the detection limit (<0.01 mg/m 3 ) but the number concentration was similar to tap water. The size distribution pattern with tap water and high-silica water was similar to a previous report [ 22 ] (Figure 1 A). The humidifier generated visible fog (micro-sized water droplets) and submicro-sized residuals; however, because the SMA-CPC system could detect particles with diameter 10–410 nm, we characterized only the residuals as particles but not obtain size distribution data of the primary water droplets of the humidifier.…”

Section: Resultssupporting

confidence: 89%

Effect of aerosol particles generated by ultrasonic humidifiers on the lung in mouse

et al. 2013

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BackgroundUltrasonic humidifiers silently generate water droplets as a cool fog and produce most of the dissolved minerals in the fog in the form of an aerosolized “white dust.” However, the health effect of these airborne particles is largely unknown. This study aimed to characterize the aerosol particles generated by ultrasonic humidifiers and to investigate their effect on the lung tissue of mice.MethodsAn ultrasonic humidifier was operated with tap water, high-silica water, ultrapure water, or other water types. In a chamber (0.765 m3, ventilation ratio 11.5 m3/hr), male ICR mice (10-week-old) were exposed by inhalation to an aerosol-containing vapor generated by the humidifier. After exposure for 7 or 14 days, lung tissues and bronchoalveolar lavage fluid (BALF) were collected from each mouse and examined by microarray, quantitative reverse transcription-polymerase chain reaction, and light and electron microscopy.ResultsParticles generated from the humidifier operated with tap water had a mass concentration of 0.46 ± 0.03 mg/m3, number concentration of (5.0 ± 1.1) × 104/cm3, and peak size distribution of 183 nm. The particles were phagocytosed by alveolar macrophages in the lung of mice. Inhalation of particles caused dysregulation of genes related to mitosis, cell adhesion molecules, MHC molecules and endocytosis, but did not induce any signs of inflammation or tissue injury in the lung.ConclusionThese results indicate that aerosol particles released from ultrasonic humidifiers operated with tap water initiated a cellular response but did not cause severe acute inflammation in pulmonary tissue. Additionally, high mineral content tap water is not recommended and de-mineralized water should be recommended in order to exclude any adverse effects.

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Section: Resultssupporting

confidence: 89%

Effect of aerosol particles generated by ultrasonic humidifiers on the lung in mouse

et al. 2013

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“…More readings with an RH over 100% were observed in the ultrasonic chamber than in the nanomist chamber. This difference could be one reason that the number density of mists produced by the ultrasonic humidifier was four times greater than the nanomist humidifier (Hung et al, 2010b).…”

Section: Resultsmentioning

confidence: 99%

“…These mists are occasionally generated by ultrasonic humidifiers, and their average particle diameters vary between 2.9 lm (Rodes et al, 1990) and 216 nm (Hung et al, 2010b). The large mists can easily wet the surface of produce, which is covered by a laminar film of water.…”

Section: Introductionmentioning

confidence: 99%

Controlling the weight loss of fresh produce during postharvest storage under a nano-size mist environment

Hung

Tong

Tanaka

et al. 2011

Journal of Food Engineering

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“…A number of studies have provided information on the particle size distribution of aerosols generated by ultrasonic humidifiers [34, 35, 67, 68]. Rodes et al [34] reported a count median diameter of 1.8 μ m and a mass median diameter of 2.9 μ m for wet aerosols from an ultrasonic humidifier using tap water with a total dissolved solids concentration of about 100 mg/L.…”

Section: Application and Discussionmentioning

confidence: 99%

“…After drying, Rhodes et al [34] estimated that the count median diameter for the aerosols from the tap water was about 0.1 μ m. Highsmith et al [35] reported count median diameters of about 0.2—0.3 μ m for dry aerosols generated by an ultrasonic humidifier using tap water with a total dissolved solids concentration of about 300 mg/L. Hung et al [67] (water type not specified) and Umezawa et al [68] (using tap water) both reported particle size distributions for dry aerosols with peaks at about 0.2 μ m. Hung et al [67] found that the size distributions peaked at about the same aerosol size for both ambient (22°C and 70% relative humidity) and cold-storage (about 5°C and 80-90% relative humidity) conditions. No studies were identified that estimated deposition fractions for inhalation exposures associated with humidifier use.…”

Section: Application and Discussionmentioning

confidence: 99%

Assessing Inhalation Exposures Associated with Contamination Events in Water Distribution Systems

2016

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When a water distribution system (WDS) is contaminated, short-term inhalation exposures to airborne contaminants could occur as the result of domestic water use. The most important domestic sources of such exposures are likely to be showering and the use of aerosol-producing humidifiers, i.e., ultrasonic and impeller (cool-mist) units. A framework is presented for assessing the potential effects of short-term, system-wide inhalation exposures that could result from such activities during a contamination event. This framework utilizes available statistical models for showering frequency and duration, available exposure models for showering and humidifier use, and experimental results on both aerosol generation and the volatilization of chemicals during showering. New models for the times when showering occurs are developed using time-use data for the United States. Given a lack of similar models for how humidifiers are used, or the information needed to develop them, an analysis of the sensitivity of results to assumptions concerning humidifier use is presented. The framework is applied using network models for three actual WDSs. Simple models are developed for estimating upper bounds on the potential effects of system-wide inhalation exposures associated with showering and humidifier use. From a system-wide, population perspective, showering could result in significant inhalation doses of volatile chemical contaminants, and humidifier use could result in significant inhalation doses of microbial contaminants during a contamination event. From a system-wide perspective, showering is unlikely to be associated with significant doses of microbial contaminants. Given the potential importance of humidifiers as a source of airborne contaminants during a contamination event, an improved understanding of the nature of humidifier use is warranted.

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Measurements of particle size distributions produced by humidifiers operating in high humidity storage environments

Cited by 27 publications

References 15 publications

Effect of aerosol particles generated by ultrasonic humidifiers on the lung in mouse

Effect of aerosol particles generated by ultrasonic humidifiers on the lung in mouse

Controlling the weight loss of fresh produce during postharvest storage under a nano-size mist environment

Assessing Inhalation Exposures Associated with Contamination Events in Water Distribution Systems

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