Emission of iron and aluminum oxide particles from ultrasonic humidifiers and potential for inhalation

Yao, Wenchuo; Gallagher, Daniel L.; Marr, Linsey C.; Dietrich, Andrea M.

doi:10.1016/j.watres.2019.114899

Cited by 14 publications

(15 citation statements)

References 45 publications

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“…The mechanism may contribute to the observation that proportionally more water is emitted from the humidifier than metals or elements. As previously demonstrated by Sain and Dietrich (2015) and Yao et al. (2019) , the humidifier emits aerosols with slightly lower concentrations of minerals (e.g., 85–90%) than present in the fill water.…”

Section: Discussionmentioning

confidence: 55%

“…The airborne particle concentration after 8 h (at steady-state) was 211 μg/m 3 based on total ICP-MS elements collected on impactor, while the total calculated mass concentration from SMPS was 320 μg/m 3 . This difference may be explained through bicarbonate, which cannot be measured by ICP-MS, and constitutes about 35% of the total dissolved solids in Blackburg tap water ( Sain and Dietrich, 2015 ; Yao et al., 2019 ). If bicarbonate is assumed to be 35% of TDS and total ICP-MS elements measures all anions/cations except bicarbonate, then total ICP-MS elements plus bicarbonate would be 324 μg/m 3 , a value very similar to that measured by SMPS.…”

Section: Resultsmentioning

confidence: 99%

“…Previous research ( Sain and Dietrich, 2015 ; Yao et al., 2019 ) demonstrates that, over time, the metals and inorganic elements in the humidifier reservoir increase in concentration indicating that more pure water is emitted and the metals and elements concentrate within the reservoir. This suggests that particles emitted from the humidifier do not have the same elemental concentrations as the initial fill water.…”

Section: Introductionmentioning

confidence: 93%

“…PM 10 of 118 and 966 μg/m 3 were emitted in a closed dormitory room of 33.5 m 3 and air exchange rate of 0.87 hr −1 when using 75 and 510 mg/L TDS tap water to fill the humidifiers of water consumption rate at 0.21 L/h, respectively ( Sain and Dietrich, 2015 ). Soluble minerals and insoluble metal oxide particles, when present in fill water in the humidifiers, are emitted as sub-micron, inhalable particulates ( Sain et al., 2018 ; Yao et al., 2019 ). Particles <1 μm can penetrate deeper into the lower lung region and cause mild to severe inflammatory responses depending on the chemical composition.…”

Section: Introductionmentioning

confidence: 99%

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An overlooked route of inhalation exposure to tap water constituents for children and adults: Aerosolized aqueous minerals from ultrasonic humidifiers

2020

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Fine particulates and aerosols emitted by commonly used, room-sized ultrasonic humidifiers may pose adverse health effects to children and adults. The literature documents adverse effects for children exposed to minerals emitted from humidifiers. This study performs novel and comprehensive characterization of bivariate particle size and element concentrations of emitted airborne aerosols and particles from ultrasonic humidifiers filled with tap water, including size distribution from 0.014 to 10 μm by scanning mobility particle sizer and AeroTrak; corresponding metal and elemental concentrations as a function of particle size by inductively coupled plasma mass spectrometer; and calculations of deposition fraction in human lungs for age-specific groups using the multi-path particle dosimetry model (MPPD). Deposition fraction is the ratio of mass deposited to total mass inhaled. When filled with tap water, water evaporated from emitted aerosols to form submicron particles that became essentially “dried tap water” with median size 146 nm and mean concentration of 211 μg-total elements/m 3 -air including 35 μg-calcium/m 3 -air in a room of 33.5 m 3 and air exchange rate at ∼0.8 hr −1 . Approximately 90% of emitted particles deposited in human lungs were <1 μm as shown by MPPD model. The smaller particles contained little water and higher concentration of minerals, while larger particles of >1 μm consisted of lower elemental concentrations and more water due to low evaporation. Deposition fraction in pulmonary region was ∼2-fold higher, and deposited particulate mass was 3.5-fold higher for children than adults, indicating greater inhalation exposure to children compared to adults. Modeled data of total particles mass per body weight (BW) that will deposit in adult and child lungs after 8-h humidifier exposure were respectively 2.8 μg/kg-BW and 9.8 μg/kg-BW, where calcium contributes 0.4 μg/kg-BW and 1.6 μg/kg-BW. This comprehensive study of bivariate inorganic chemical composition as a function of particle size expanded, quantified, and modeled exposure for children and adults to aerosolized calcium and other inorganic constituents in water.

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Section: Discussionmentioning

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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An overlooked route of inhalation exposure to tap water constituents for children and adults: Aerosolized aqueous minerals from ultrasonic humidifiers

2020

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“…They concluded that PM‐bound elements, including Ca, K, Cl, S, and Si, exhibit linear correlation with their concentrations in the charge water (water used for humidification). Yao et al 32 employed ICP mass spectrometry (ICP‐MS) and measured the metallic component of humidifier‐generated PM, with a specific focus on Fe and Al. These studies established that PM emitted from humidifiers is predominantly composed of inorganic compounds, with its composition directly mirroring that in the charge water.…”

Section: Introductionmentioning

confidence: 99%

Particulate matter emitted from ultrasonic humidifiers—Chemical composition and implication to indoor air

et al. 2020

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Household humidification is widely practiced to combat dry indoor air. While the benefits of household humidification are widely perceived, its implications to the indoor air have not been critically appraised. In particular, ultrasonic humidifiers are known to generate fine particulate matter (PM). In this study, we first conducted laboratory experiments to investigate the size, quantity, and chemical composition of PM generated by an ultrasonic humidifier. The mass of PM generated showed a correlation with the total alkalinity of charge water, suggesting that CaCO 3 is likely making a major contribution to PM. Ion chromatography analysis revealed a large amount of SO 4 2− in PM, representing a previously unrecognized indoor source. Preliminary results of organic compounds being present in humidifier PM are also presented. A whole-house experiment was further conducted at an actual residential house, with five low-cost sensors (AirBeam) monitoring PM in real time. Operation of a single ultrasonic humidifier resulted in PM 2.5 concentrations up to hundreds of μg m −3 , and its influence extended across the entire household. The transport and loss of PM 2.5 depended on the rate of air circulation and ventilation. This study emphasizes the need to further investigate the impact of humidifier operation, both on human health and on the indoor atmospheric chemistry, for example, partitioning of acidic and basic compounds.

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Machine Learning and IoT-Based Ultrasonic Humidification Control System for Longevity of Fruits and Vegetables

Gautham¹,

Mujahid²,

Kanagaraj³

et al. 2021

Proceedings of International Conference on Computational Intelligence

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Emission of iron and aluminum oxide particles from ultrasonic humidifiers and potential for inhalation

Cited by 14 publications

References 45 publications

An overlooked route of inhalation exposure to tap water constituents for children and adults: Aerosolized aqueous minerals from ultrasonic humidifiers

An overlooked route of inhalation exposure to tap water constituents for children and adults: Aerosolized aqueous minerals from ultrasonic humidifiers

Particulate matter emitted from ultrasonic humidifiers—Chemical composition and implication to indoor air

Machine Learning and IoT-Based Ultrasonic Humidification Control System for Longevity of Fruits and Vegetables

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