Fletcher A M, Pickering C A, Custovic A, Simpson J, Kennaugh J, Woodcock A
North West Lung Centre, Wythenshawe Hospital, Manchester, UK.
Clin Exp Allergy. 1996 Sep;26(9):1051-6. doi: 10.1111/j.1365-2222.1996.tb00643.x.
Low humidity is an important limiting factor for mite population growth. Reducing humidity can therefore be used as a method to control mites within the home.
This study investigated the effect of mechanical ventilation heat recovery (MVHR) units on house dust mites and mite allergen Der p 1 in typical homes in the North-West of England.
Mite counts and Der p 1 levels were measured at 3-monthly intervals over a period of 1 year in 18 houses (nine with MVHR units and nine architecturally matched control houses). Paired dust samples were collected using a vacuum cleaner with an air-flow rate 451/sec, adapted to collect the sample onto a preweighed filter paper. A 1 m2 area of bedroom carpet, living room carpet and mattress was sampled for 2 min. Indoor temperature and relative humidity (RH) levels were recorded for a period of 1 week before and after the winter period (November and February: 3 and 6 months data sets). The environmental questionnaire was completed at the beginning and at the end of the study.
No difference in either Der p 1 concentrations or mite counts in any of the sampling sites at 3, 6, 9 and 12 months as compared with the baseline values was found, both within and between the groups (P > 0.01). The measured levels of RH performed in autumn and winter were found to be lower in the MVHR houses compared to the architectural controls. The indoor temperature during each period did not differ between the groups. Questionnaire data showed that the severity of condensation improved in the MVHR homes, whilst during the winter period, the severity of condensation had increased in the architectural control group.
The MVHR unit does not reduce indoor humidity to levels capable of retarding the mite population growth and decreasing mite allergens in the type of houses predominantly found in the mild and humid climate of the North-West of England.
低湿度是螨虫种群增长的一个重要限制因素。因此，降低湿度可作为一种控制家庭中螨虫的方法。
本研究调查了机械通风热回收（MVHR）装置对英格兰西北部典型家庭中屋尘螨及螨过敏原Der p 1的影响。
在18所房屋（9所安装了MVHR装置，9所建筑结构匹配的对照房屋）中，于1年时间内每隔3个月测量一次螨虫数量和Der p 1水平。使用气流速度为451/秒的真空吸尘器收集配对的灰尘样本，该吸尘器经过改装，可将样本收集到预先称重的滤纸上。对卧室地毯、客厅地毯和床垫1平方米的区域进行2分钟采样。在冬季前后各记录1周的室内温度和相对湿度（RH）水平（11月和2月：3个月和6个月的数据集）。在研究开始和结束时完成环境调查问卷。
在3、6、9和12个月时，各采样点的Der p 1浓度和螨虫数量与基线值相比，组内和组间均未发现差异（P>0.01）。发现与建筑结构对照房屋相比，MVHR房屋在秋冬季节测量的RH水平较低。各时间段内两组的室内温度无差异。调查问卷数据显示，MVHR房屋中凝结现象的严重程度有所改善，而在冬季，建筑结构对照房屋组中凝结现象的严重程度有所增加。
在英格兰西北部温和湿润气候下常见的房屋类型中，MVHR装置并不能将室内湿度降低到足以抑制螨虫种群增长和减少螨过敏原的水平。
