Predictors of indoor absolute humidity and estimated effects on influenza virus survival in grade schools
Predictors of indoor absolute humidity and estimated effects on influenza virus survival in grade schools
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DOI：
10.1186/1471-2334-13-71
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发表时间：
2013-02-05
影响因子：
3.7
通讯作者：
Huskins, W. Charles
中科院分区：
文献类型：
--
作者：
Koep, Tyler H.;Enders, Felicity T.;Huskins, W. Charles
背景：低绝对湿度（AH）与流感病毒存活率和传播性的增加以及季节性流感暴发的发生有关。室内环境加湿可减轻病毒传播，可能是一项重要的控制策略，特别是在病毒传播常见并有助于流感在社区传播的学校。然而，室内学校环境中AH的变异性和预测因素以及教室加湿到可能降低病毒存活率的水平的可行性尚未得到研究。方法：在连续两个冬季，采用自动传感器测量明尼苏达州两所没有中央加湿的小学的温度、湿度和二氧化碳水平。室外AH测量数据来自北美陆地数据同化系统。使用一致性相关系数（CCC）评估教室内、同一学校教室之间和学校之间室内AH的变异性。采用时间序列自回归条件异方差模型检验室内AH的预测因子。教室加湿器在学校不上课时使用，以评估将室内AH增加到与流感病毒存活率降低相关的水平的可行性，正如先前发表的动物实验所预测的那样。结果：AH在教室内变化不大（CCC > 0.90），但在同一学校的教室之间（CCC 1 0.81, CCC 2 0.88）和学校之间（CCC 0.81）变化较大。室内AH在冬季变化很大（范围为2.60 - 10.34毫巴[mb]），并且与室外AH的变化密切相关（p < 0.001）。学校工作日室内AH的变化与CO2水平密切相关（p < 0.001）。在4小时内，教室加湿器使室内AH增加了4 mb，这一增加足以使冬季月份预计1小时病毒存活率的绝对值降低30%。结论：在冬季，非加湿小学的室内空气湿度变化很大，经常达到非常低的水平。室内结果是通过一个季节的室外AH和每个上学日的二氧化碳水平（可能反映人类活动）来预测的。教室加湿可能是一种可行的方法，可以将室内AH增加到可能降低流感病毒存活和传播的水平。
Background: Low 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.Methods: Automated 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.Results: AH 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.Conclusions: During 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.