Menzies School of Health Research, John Mathews Building (Bldg 58), PO Box 41096, Casuarina, NT, 0810, Australia.
Malar J. 2012 Jun 15;11:200. doi: 10.1186/1475-2875-11-200.
BACKGROUND/METHODS: Qualitative studies suggest that bed nets affect the thermal comfort of users. To understand and reduce this discomfort the effect of bed nets on temperature, humidity, and airflow was measured in rural homes in Asia and Africa, as well as in an experimental wind tunnel. Two investigators with architectural training selected 60 houses in The Gambia, Tanzania, Philippines, and Thailand. Data-loggers were used to measure indoor temperatures in hourly intervals over a 12 months period. In a subgroup of 20 houses airflow, temperature and humidity were measured at five-minute intervals for one night from 21.00 to 6.00 hrs inside and outside of bed nets using sensors and omni-directional thermo-anemometers. An investigator set up a bed net with a mesh size of 220 holes per inch 2 in each study household and slept under the bed net to simulate a realistic environment. The attenuation of airflow caused by bed nets of different mesh sizes was also measured in an experimental wind tunnel.
The highest indoor temperatures (49.0 C) were measured in The Gambia. During the hottest months of the year the mean temperature at night (9 pm) was between 33.1 C (The Gambia) and 26.2 C (Thailand). The bed net attenuated the airflow from a minimum of 27% (Philippines) to a maximum of 71% (The Gambia). Overall the bed nets reduced airflow compared to un-attenuated airflow from 9 to 4 cm sec-1 or 52% (p<0.001). In all sites, no statistically significant difference in temperature or humidity was detected between the inside and outside of the bed net. Wind tunnel experiments with 11 different mesh-sized bed nets showed an overall reduction in airflow of 64% (range 55 - 71%) compared to un-attenuated airflow. As expected, airflow decreased with increasing net mesh size. Nets with a mesh of 136 holes inch-2 reduced airflow by 55% (mean; range 51 - 73%). A denser net (200 holes inch-2) attenuated airflow by 59% (mean; range 56 - 74%).
Despite concerted efforts to increase the uptake of this intervention in many areas uptake remains poor. Bed nets reduce airflow, but have no influence on temperature and humidity. The discomfort associated with bed nets is likely to be most intolerable during the hottest and most humid period of the year, which frequently coincides with the peak of malaria vector densities and the force of pathogen transmission.
These observations suggest thermal discomfort is a factor limiting bed net use and open a range of architectural possibilities to overcome this limitation.
背景/方法：定性研究表明，蚊帐会影响使用者的热舒适度。为了理解和减少这种不适，我们测量了亚洲和非洲农村家庭以及实验风洞中蚊帐对温度、湿度和气流的影响。两位具有建筑培训背景的研究人员在冈比亚、坦桑尼亚、菲律宾和泰国选择了 60 所房屋。数据记录器用于在 12 个月的时间内每小时测量室内温度。在 20 所房屋中的一个子组中，使用传感器和全向热风速计在晚上 9 点到 6 点之间每五分钟测量一次蚊帐内外的气流、温度和湿度。一位研究人员在每个研究家庭中设置了一个网眼尺寸为每平方英寸 220 个孔的蚊帐，并在模拟真实环境下在蚊帐下睡觉。还在实验风洞中测量了不同网眼尺寸的蚊帐对气流的衰减。
最高的室内温度（49.0°C）是在冈比亚测量的。在一年中最热的几个月里，晚上 9 点的平均温度在 33.1°C（冈比亚）和 26.2°C（泰国）之间。蚊帐将气流衰减至最小 27%（菲律宾）至最大 71%（冈比亚）。总体而言，与未衰减的气流相比，蚊帐将气流减少了 9 到 4 厘米/秒或 52%（p<0.001）。在所有地点，均未检测到蚊帐内外的温度或湿度存在统计学上的显著差异。使用 11 种不同网眼尺寸的蚊帐进行的风洞实验表明，与未衰减的气流相比，气流总体减少了 64%（范围为 55%至 71%）。正如预期的那样，气流随网眼尺寸的增加而减小。网眼尺寸为 136 孔/平方英寸的蚊帐将气流减少了 55%（平均值；范围为 51%至 73%）。更密集的网（200 孔/平方英寸）将气流衰减了 59%（平均值；范围为 56%至 74%）。
尽管在许多地区都在大力推广这种干预措施，但使用率仍然很低。蚊帐会减少气流，但对温度和湿度没有影响。与蚊帐相关的不适很可能在一年中最热和最潮湿的时期最为难以忍受，而这段时期通常与疟疾媒介密度的高峰期和病原体传播的高峰期相吻合。
这些观察结果表明，热舒适度是限制蚊帐使用的一个因素，并为克服这一限制提供了一系列建筑可能性。
