Human exposure to particles at the air-water interface: Influence of water quality on indoor air quality from use of ultrasonic humidifiers

Yao, Wenchuo; Porto, Rachael Dal; Gallagher, Daniel L.; Dietrich, Andrea M.

doi:10.1016/j.envint.2020.105902

Cited by 27 publications

(45 citation statements)

References 25 publications

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“…Our results show that both the number and size of dried particles increase with increasing solute concentrations in water. This trend is consistent with observations made by Sain et al 13 The unimodal size distribution obtained here is in agreement with a few previous studies which showed that a major fraction of dried particles from an ultrasonic humidifier is in the submicrometer range 13,30,36,38,39 . However, there may be larger particles that are beyond the detection range in the current method, as shown by recent work by Yao et al 38,39 …”

Section: Resultssupporting

confidence: 94%

“…We note that the decay of the PM 2.5 signal can also be affected by a shift in PM size distribution over time. Although our SMPS results indicate that the majority of PM falls within the size range between 100 and 670 nm, we cannot rule out the possibility that larger particles at the size range between 670 nm and 2.5 μm are present 38,39 . These larger particles are expected to make significant contributions to scattering‐based detection, such as that employed by AirBeam.…”

Section: Resultsmentioning

confidence: 82%

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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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Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 82%

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

et al. 2020

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“…(2015) estimated the inhalation risks from polycyclic aromatic hydrocarbons absorbed on ambient particulates for human child and adult, and the MPPD model showed higher normalized-to-bodyweight exposure dose to child than adult. When applied to ultrasonic humidification of a conference room, the MPPD model demonstrated that inhaled and lung-deposited mass was greater when the fill water TDS was higher, and that both hard and soft waters influence lung-deposited mass for high TDS waters ( Yao et al., 2020 ). MPPD is widely employed to evaluate human exposure to particulate matter (see Table S2 in Supporting Information for summary of environmental applications involving the MPPD model).…”

Section: Introductionmentioning

confidence: 99%

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

2020

Self Cite

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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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“…Among these, the use of humidifiers to prevent respiratory diseases and improve the indoor thermal environment significantly contribute to the increase in the indoor PM concentration [12]. In the USA, approximately 17.2 million households use humidifiers [13]. Similarly, considering the climate in South Korea, wherein temperature and humidity are low during winter, it is believed that most Koreans use humidifiers [14].…”

Section: Introductionmentioning

confidence: 99%

“…Here, instruments based on light scattering enable real-time measurement of particle concentrations at a significantly lower cost than the gravimetric and equivalent methods [24]. In addition, since the PM concentration can vary depending on the distance from the parts that emit moisture, various measuring points are required for the experiment [13]. In this case, minimizing errors in the measurement is necessary by unifying the measured values among the equipment.…”

Section: Introductionmentioning

confidence: 99%

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

Park

Seo

Lee

2020

IJERPH

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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.

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Human exposure to particles at the air-water interface: Influence of water quality on indoor air quality from use of ultrasonic humidifiers

Cited by 27 publications

References 25 publications

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

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

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

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

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