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Dietrich AM, Yao W, Gohlke JM, Gallagher DL. Environmental risks from consumer products: Acceptable drinking water quality can produce unacceptable indoor air quality with ultrasonic humidifier use. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 856:158787. [PMID: 36116655 DOI: 10.1016/j.scitotenv.2022.158787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/10/2022] [Accepted: 09/11/2022] [Indexed: 06/15/2023]
Abstract
The commonly used consumer product of an ultrasonic humidifier (e.g., cool mist humidifier) emits fine particles containing metals from tap water used to fill the humidifier. The objectives are: 1) predict emitted indoor air inhalable metal concentrations produced by an ultrasonic humidifier filled with tap-water containing As, Cd, Cr, Cu, Mn, and Pb in 33 m3 or 72 m3 rooms with varying air exchange rates; 2) calculate daily ingestion and 8-h inhalation average daily dose (ADD) and hazard quotient (HQ) for adults and children (aged 0.25-6 yr); and 3) quantify deposition in respiratory tract via multi-path particle dosimetry (MPPD) model. Mass concentrations of indoor air metals increase proportionally with aqueous metal concentrations in fill water, and are inversely related to ventilation. Inhalation-ADDs are 2 magnitudes lower than ingestion-ADDs, using identical water quality for ingestion and fill-water. However, in the 33 m3, low 0.2/h ventilated room, inhalation-HQs are >1 for children and adults, except for Pb. HQ inhalation risks exceed ingestion risks at drinking water regulated levels for As, Cd, Cr, and Mn. MPPD shows greater dose deposits in lungs of children than adults, and 3 times greater deposited doses in a 33 m3 vs 72 m3 room. Rethinking health effects of drinking water and consumer products to broaden consideration of multiple exposure routes is needed.
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Affiliation(s)
- Andrea M Dietrich
- Department of Civil & Environmental Engineering, Virginia Tech, Blacksburg, VA, USA.
| | - Wenchuo Yao
- Department of Civil & Environmental Engineering, Virginia Tech, Blacksburg, VA, USA
| | - Julia M Gohlke
- Department of Population Health Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Daniel L Gallagher
- Department of Civil & Environmental Engineering, Virginia Tech, Blacksburg, VA, USA
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Dietrich AM, Yao W, Gallagher DL. Exposure at the indoor water-air interface: Fill water constituents and the consequent air emissions from ultrasonic humidifiers: A systematic review. INDOOR AIR 2022; 32:e13129. [PMID: 36437646 PMCID: PMC9828259 DOI: 10.1111/ina.13129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/24/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
This systematic review investigates the emissions from ultrasonic humidifiers (e.g., cool mist humidifiers) within indoor air environments, namely soluble and insoluble metals and minerals as well as microorganisms and one organic chemical biocide. Relationships between ultrasonic humidifier fill water quality and the emissions in indoor air are studied, and associated potential adverse health outcomes are discussed. Literature from January 1, 1980, to February 1, 2022, was searched from online databases of PubMed, Web of Science, and Scopus to produce 27 articles. The results revealed clear positive proportional relationships of the concentration of microorganisms and soluble metals/minerals between fill water qualities and emitted airborne particles, for both microbial (n = 9) and inorganic (n = 15) constituents. When evaluating emissions and the consequent health outcomes, ventilation rates of specific exposure scenarios affect the concentrations of emitted particles. Thus, well-ventilated rooms may alleviate inhalation risks when the fill water in ultrasonic humidifiers contains microorganisms and soluble metals/minerals. Case reports (n = 3) possibly due to the inhalation of particles from ultrasonic humidifier include hypersensitivity pneumonitis in adults and a 6-month infant; the young infant exhibited nonreversible mild obstructive ventilator defect. In summary, related literature indicated correlation between fill water quality of ultrasonic humidifier and emitted particles in air quality, and inhalation of the emitted particles may cause undesirable health outcomes of impaired respiratory functions in adults and children.
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Affiliation(s)
- Andrea M. Dietrich
- Department of Civil and Environmental EngineeringVirginia TechBlacksburgVirginiaUSA
| | - Wenchuo Yao
- Department of Civil and Environmental EngineeringVirginia TechBlacksburgVirginiaUSA
| | - Daniel L. Gallagher
- Department of Civil and Environmental EngineeringVirginia TechBlacksburgVirginiaUSA
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Duan M, Lu Y, Li Y, Wei J, Qian H, Lin B, Liu L. Indoor dryness and humidification-induced arsenic inhalation exposure above 4200 m in Ngari, China. INDOOR AIR 2022; 32:e13133. [PMID: 36305059 DOI: 10.1111/ina.13133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 09/14/2022] [Accepted: 09/27/2022] [Indexed: 06/16/2023]
Abstract
Ngari Prefecture, Tibet, China, features its ultrahigh altitude above 4200 m, very little annual precipitation and extremely low relative humidity. Residents who have migrated to Tibet from the plains use indoor humidification to reduce the respiratory discomfort caused by prolonged exposure to dry indoor air. In this study, field investigations and analysis of residential indoor environments and humidification methods in Ngari Prefecture revealed that ninety-eight percent of humidifier consumers in the prefecture used low-cost ultrasonic humidifiers filled with indoor tap water. The results revealed that the arsenic (As) concentration of the tap water was 41.6 μg/L, over four times China's standards for drinking water quality (10 μg/L). The source As concentration in the air humidified by the tap water-filled ultrasonic humidifier is (619.8 ± 59.1) (ng/m3 ·air), while no As was detected in the air humidified by the evaporative humidifier. For ultrasonic humidifier with tap water-filled, the inhalation dose of a healthy adult was 45.4 ng/d. The minute ventilation volume of migrated residents who had been in Ngari for less than two years (12.5 ± 4.3 L/min) was greater than those of the long-term residents (10.0 ± 4.5 L/min), which may exacerbate the short-term inhalation exposure risk for migrated residents. To reduce the health risks associated with As exposure, evaporative humidifiers are recommended for households using domestic water. If ultrasonic humidifiers are used, the tap water must be purified with terminal filters.
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Affiliation(s)
- Mengjie Duan
- Vanke School of Public Health, Tsinghua University, Beijing, China
- Department of Building Science, Tsinghua University, Beijing, China
- Laboratory of Eco-Planning & Green Building, Ministry of Education, Tsinghua University, Beijing, China
| | - Yiran Lu
- Department of Building Science, Tsinghua University, Beijing, China
- Laboratory of Eco-Planning & Green Building, Ministry of Education, Tsinghua University, Beijing, China
| | - Yifan Li
- Department of Building Science, Tsinghua University, Beijing, China
- Laboratory of Eco-Planning & Green Building, Ministry of Education, Tsinghua University, Beijing, China
| | - Jianjian Wei
- Institute of Refrigeration and Cryogenics, Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Hua Qian
- School of Energy and Environment, Southeast University, Nanjing, China
| | - Borong Lin
- Department of Building Science, Tsinghua University, Beijing, China
- Laboratory of Eco-Planning & Green Building, Ministry of Education, Tsinghua University, Beijing, China
| | - Li Liu
- Department of Building Science, Tsinghua University, Beijing, China
- Laboratory of Eco-Planning & Green Building, Ministry of Education, Tsinghua University, Beijing, China
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Yao W, Gallagher DL, Dietrich AM. Risks to children from inhalation of aerosolized aqueous manganese emitted from ultrasonic humidifiers can be greater than for corresponding ingestion. WATER RESEARCH 2021; 207:117760. [PMID: 34800908 DOI: 10.1016/j.watres.2021.117760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/22/2021] [Accepted: 10/10/2021] [Indexed: 06/13/2023]
Abstract
UNLABELLED The essential trace element manganese (Mn) can cause neurotoxicity with inhalation acknowledged as a more severe health and cognition threat than ingestion. METHODS Over a range of aqueous Mn concentrations present in tap water, this research characterizes exposures and risks for adults and 0.25, 1, 2.5, and 6 yr old children who ingest the water and inhale respirable particles produced by a room-sized ultrasonic humidifier filled with the same water. Aqueous Mn concentrations evaluated included 50 µg/L USEPA esthetic guideline, 80 µg/L WHO infant guideline, and 120 µg/L Canadian regulatory level. Airborne-particle-bound Mn concentrations were generated for water filling an ultrasonic humidifier under four realistic room conditions (33 m3 small or 72 m3 large) with varying ventilation rates from 0.2/h -1.5/h. Average daily doses (ADD) and reference intake doses were calculated for ingestion and 8-h inhalation of humidified air. Hazard quotients (HQ) compared the intake doses and reference doses. Multi-path particle dosimetry (MPPD) model quantified the particle deposition and deposited dose in children's and adults' respiratory tracts. RESULTS At only 11 µg/L Mn, the resulting humidified air Mn exceeds USEPA's reference concentration of 0.05 µg/m3 Mn in small room with low, energy-efficient ventilation. Inhalation ADD are 2 magnitudes lower than ingestion ADD for identical water Mn concentrations and daily exposure frequency. Even so, ingestion HQs are approximately 0.2 but inhalation risk is significant (HQ>1) for children and adults when breathing Mn-humidified air under most small room conditions at 50, 80 or 120 µg/L Mn. MPPD model indicates inhaled Mn deposits in head and pulmonary regions, with greater Mn dose deposits in children than adults. CONCLUSION Inhalation of Mn-particles produced from ultrasonic humidifiers can pose greater risks than ingestion at the same water concentration, especially for children. Aqueous Mn concentration and room size influence risks. Limiting manganese exposures and setting regulations requires consideration of both ingestion and inhalation of water.
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Affiliation(s)
- Wenchuo Yao
- Department of Civil and Environmental Engineering, Virginia Tech, 413 Durham Hall, Blacksburg, Virginia 24061, United States
| | - Daniel L Gallagher
- Department of Civil and Environmental Engineering, Virginia Tech, 413 Durham Hall, Blacksburg, Virginia 24061, United States
| | - Andrea M Dietrich
- Department of Civil and Environmental Engineering, Virginia Tech, 413 Durham Hall, Blacksburg, Virginia 24061, United States.
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Li J, Xu W, Li Z, Duan M, Ouyang B, Zhou S, Lei L, He Y, Sun J, Wang Z, Du L, Sun Y. Real-time characterization of aerosol particle composition, sources and influences of increased ventilation and humidity in an office. INDOOR AIR 2021; 31:1364-1376. [PMID: 33876836 DOI: 10.1111/ina.12838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
Most of human exposure to atmospheric pollutants occurs indoors, and the components of outdoor aerosols may have been changed in the way before reaching indoor spaces. Here we conducted real-time online measurements of mass concentrations and chemical composition of black carbon and the non-refractory species in PM2.5 in an occupied office for approximately one month. The open-close windows and controlled dampness experiments were also performed. Our results show that indoor aerosol species primarily originate from outdoors with indoor/outdoor ratio of these species typically less than unity except for certain organic aerosol (OA) factors. All aerosol species went through filtration upon transport indoors. Ammonium nitrate and fossil fuel OA underwent evaporation or particle-to-gas partitioning, while less oxidized secondary OA (SOA) underwent secondary formation and cooking OA might have indoor sources. With higher particulate matter (PM) mass concentration outdoors than in the office, elevated natural ventilation increased PM exposure indoors and this increased exposure was prolonged when outdoor PM was scavenged. We found that increasing humidity in the office led to higher indoor PM mass concentration particularly more oxidized SOA. Overall, our results highlight that indoor exposure of occupants is substantially different from outdoor in terms of mass concentrations and chemical species.
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Affiliation(s)
- Junyao Li
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Weiqi Xu
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Zhijie Li
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Minzheng Duan
- Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Bin Ouyang
- Cambri Environmental Technology Co., Ltd., Houston, TX, USA
| | - Shan Zhou
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, USA
| | - Lu Lei
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yao He
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Jiaxing Sun
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Zifa Wang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Lin Du
- Environment Research Institute, Shandong University, Qingdao, China
| | - Yele Sun
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
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Lau CJ, Loebel Roson M, Klimchuk KM, Gautam T, Zhao B, Zhao R. Particulate matter emitted from ultrasonic humidifiers-Chemical composition and implication to indoor air. INDOOR AIR 2021; 31:769-782. [PMID: 33108019 DOI: 10.1111/ina.12765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 10/04/2020] [Accepted: 10/16/2020] [Indexed: 05/04/2023]
Abstract
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 CaCO3 is likely making a major contribution to PM. Ion chromatography analysis revealed a large amount of SO42- 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 PM2.5 concentrations up to hundreds of μg m-3 , and its influence extended across the entire household. The transport and loss of PM2.5 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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Affiliation(s)
- Chester J Lau
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada
| | - Max Loebel Roson
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada
| | - Keifer M Klimchuk
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada
| | - Tania Gautam
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada
| | - Boyang Zhao
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada
| | - Ran Zhao
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada
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