US EPA

7530876 

Journal Article 

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

Lau, CJ; Loebel Roson, Max; Klimchuk, KM; Gautam, T; Zhao, B; Zhao, Ran 

2021 

Yes 

Indoor Air
ISSN: 0905-6947
EISSN: 1600-0668 

WILEY 

HOBOKEN 

31 

3 

769-782 

English 

33108019 

10.1111/ina.12765 

WOS:000592311000001 

https://onlinelibrary.wiley.com/doi/10.1111/ina.12765
Exit
 

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. 

air circulation and ventilation; chemical analysis; household measurement; humidifier; indoor air pollutants; Indoor air quality; particulate matter