Airflow attenuation and bed net utilization: observations from Africa and Asia
Airflow attenuation and bed net utilization: observations from Africa and Asia
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DOI：
10.1186/1475-2875-11-200
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发表时间：
2012-06-15
期刊：
影响因子：
3
通讯作者：
Knudsen, Jakob B.
中科院分区：
文献类型：
--
作者：
von Seidlein, Lorenz;Ikonomidis, Konstantin;Knudsen, Jakob B.
背景/方法：定性研究表明，蚊帐会影响使用者的热舒适度。为了了解和减少这种不适，我们在亚洲和非洲的农村家庭以及实验性风洞中测量了蚊帐对温度、湿度和气流的影响。两名接受过建筑学培训的调查员在冈比亚、坦桑尼亚、菲律宾和泰国挑选了 60 栋房屋。数据记录仪在 12 个月的时间里每小时测量一次室内温度。在一个由 20 间房屋组成的小组中，使用传感器和全向热风速计，在一个晚上的 21 点至 6 点之间，每隔 5 分钟测量一次蚊帐内外的气流、温度和湿度。调查人员在每个研究家庭中设置了网格尺寸为每英寸 220 个孔(2) 的蚊帐，并在蚊帐下睡觉以模拟现实环境。还在实验风洞中测量了不同网目尺寸的床网引起的气流衰减。结果：在冈比亚测得最高室内温度（49.0℃）。在一年中最热的月份，夜间（晚上 9 点）平均气温在 33.1 C（冈比亚）和 26.2 C（泰国）之间。蚊帐对气流的衰减从最小 27%（菲律宾）到最大 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 至 4 厘米秒(-1) 或 52% (p < 0.001)。在所有地点，蚊帐内部和外部之间的温度或湿度没有检测到统计学上的显着差异。使用 11 种不同网目大小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 55 - 71%）。正如预期的那样，气流随着网目尺寸的增加而减少。网眼为 136 孔英寸(-2) 的网减少了 55% 的气流（平均值；范围 51 - 73%）。更密集的网（200 孔英寸 2）使气流减弱 59%（平均值；范围 56 - 74%）。讨论：尽管在许多地区共同努力提高这种干预措施的采用率，但采用率仍然很低。蚊帐会减少气流，但对温度和湿度没有影响。在一年中最热和最潮湿的时期，与蚊帐相关的不适可能是最难以忍受的，这通常与疟疾媒介密度和病原体传播强度的峰值一致。结论：这些观察结果表明，热不适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。
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.Results: 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%).Discussion: 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.Conclusions: These observations suggest thermal discomfort is a factor limiting bed net use and open a range of architectural possibilities to overcome this limitation.