Predictors of indoor absolute humidity and estimated effects on influenza virus survival in grade schools

BMC Infectious Diseases

Research Article

Marc Lipsitch¹  Tyler H Koep²  Chris Pierret³  Stephen C Ekker³  Kevin L Neff³  Jeffrey Shaman⁴  Dale Krageschmidt⁵  Felicity T Enders⁶  W Charles Huskins⁷ 

[1]Center for Communicable Disease Dynamics, Department of Epidemiology and Department of Immunology and Infectious Diseases, Harvard School of Public Health, 02115, Boston, MA, USA

[2]Clinical and Translational Sciences, Mayo Graduate School, Mayo Clinic, 55905, Rochester, MN, USA

[3]Department of Biochemistry and Molecular Biology, Mayo Clinic, 55905, Rochester, MN, USA

[4]Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, 10032, New York, NY, USA

[5]Department of Facilities and Support Services, Mayo Clinic, 55905, Rochester, MN, USA

[6]Department of Health Sciences Research, Mayo Clinic, 55905, Rochester, MN, USA

[7]Division of Pediatric Infectious Diseases, Department of Pediatric and Adolescent Medicine, Mayo Clinic Children’s Center, 55905, Rochester, MN, USA

关键词: Influenza;    Humidity;    Schools;    Climate;   

DOI  :  10.1186/1471-2334-13-71

 received in 2012-11-13, accepted in 2013-01-29,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundLow absolute humidity (AH) has been associated with increased influenza virus survival and transmissibility and the onset of seasonal influenza outbreaks. Humidification of indoor environments may mitigate viral transmission and may be an important control strategy, particularly in schools where viral transmission is common and contributes to the spread of influenza in communities. However, the variability and predictors of AH in the indoor school environment and the feasibility of classroom humidification to levels that could decrease viral survival have not been studied.MethodsAutomated sensors were used to measure temperature, humidity and CO2 levels in two Minnesota grade schools without central humidification during two successive winters. Outdoor AH measurements were derived from the North American Land Data Assimilation System. Variability in indoor AH within classrooms, between classrooms in the same school, and between schools was assessed using concordance correlation coefficients (CCC). Predictors of indoor AH were examined using time-series Auto-Regressive Conditional Heteroskedasticity models. Classroom humidifiers were used when school was not in session to assess the feasibility of increasing indoor AH to levels associated with decreased influenza virus survival, as projected from previously published animal experiments.ResultsAH varied little within classrooms (CCC >0.90) but was more variable between classrooms in the same school (CCC 0.81 for School 1, 0.88 for School 2) and between schools (CCC 0.81). Indoor AH varied widely during the winter (range 2.60 to 10.34 millibars [mb]) and was strongly associated with changes in outdoor AH (p < 0.001). Changes in indoor AH on school weekdays were strongly associated with CO2 levels (p < 0.001). Over 4 hours, classroom humidifiers increased indoor AH by 4 mb, an increase sufficient to decrease projected 1-hour virus survival by an absolute value of 30% during winter months.ConclusionsDuring winter, indoor AH in non-humidified grade schools varies substantially and often to levels that are very low. Indoor results are predicted by outdoor AH over a season and CO2 levels (which likely reflects human activity) during individual school days. Classroom humidification may be a feasible approach to increase indoor AH to levels that may decrease influenza virus survival and transmission.

【 授权许可】

Unknown   
© Koep et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.