School of Public Health, University of Michigan, Ann Arbor, MI 48109-2029, USA.
Indoor Air. 2012 Jun;22(3):235-52. doi: 10.1111/j.1600-0668.2011.00761.x. Epub 2012 Feb 4.
This study, a randomized controlled trial, evaluated the effectiveness of free-standing air filters and window air conditioners (ACs) in 126 low-income households of children with asthma. Households were randomized into a control group, a group receiving a free-standing HEPA filter placed in the child's sleeping area, and a group receiving the filter and a window-mounted AC. Indoor air quality (IAQ) was monitored for week-long periods over three to four seasons. High concentrations of particulate matter (PM) and carbon dioxide were frequently seen. When IAQ was monitored, filters reduced PM levels in the child's bedroom by an average of 50%. Filter use varied greatly among households and declined over time, for example, during weeks when pollutants were monitored, filter use was initially high, averaging 84±27%, but dropped to 63±33% in subsequent seasons. In months when households were not visited, use averaged only 34±30%. Filter effectiveness did not vary in homes with central or room ACs. The study shows that measurements over multiple seasons are needed to characterize air quality and filter performance. The effectiveness of interventions using free-standing air filters depends on occupant behavior, and strategies to ensure filter use should be an integral part of interventions.
Environmental tobacco smoke (ETS) increased particulate matter (PM) levels by about 14 μg/m3 and was often detected using ETS-specific tracers despite restrictions on smoking in the house as reported on questionnaires administered to caregivers. PM concentrations depended on season, filter usage, relative humidity, air exchange ratios, number of children, outdoor PM levels, sweeping/dusting, and presence of a central air conditioner (AC). Free-standing air filters can be an effective intervention that provides substantial reductions in PM concentrations if the filters are used. However, filter use was variable across the study population and declined over the study duration, and thus strategies are needed to encourage and maintain use of filters. The variability in filter use suggests that exposure misclassification is a potential problem in intervention studies using filters. The installation of a room AC in the bedroom, intended to limit air exchange ratios, along with an air filter, did not lower PM levels more than the filter alone.
本研究为一项随机对照试验，评估了独立式空气过滤器和窗式空调（AC）在 126 户低收入哮喘儿童家庭中的有效性。家庭被随机分为对照组、接受放置在儿童卧室的高效空气过滤器（HEPA）的组以及接受过滤器和窗式 AC 的组。在三个至四个季节期间，对为期一周的室内空气质量（IAQ）进行了监测。高浓度的颗粒物（PM）和二氧化碳经常出现。当监测 IAQ 时，过滤器将儿童卧室中的 PM 水平降低了平均 50%。过滤器的使用在家庭之间差异很大，并且随着时间的推移而下降，例如，在监测污染物的几周内，过滤器的使用最初很高，平均为 84±27%，但在随后的季节中下降到 63±33%。在未进行家访的月份，平均使用量仅为 34±30%。在有中央或房间 AC 的家庭中，过滤器的有效性没有差异。该研究表明，需要进行多个季节的测量才能描述空气质量和过滤器性能。使用独立式空气过滤器的干预措施的有效性取决于居住者的行为，确保过滤器使用的策略应成为干预措施的一个组成部分。
环境烟草烟雾（ETS）使颗粒物（PM）水平增加了约 14μg/m3，尽管调查问卷中报告了对家庭内吸烟的限制，但仍使用 ETS 特定示踪剂检测到 ETS。PM 浓度取决于季节、过滤器使用情况、相对湿度、空气交换率、儿童数量、室外 PM 水平、清扫/除尘以及中央空调（AC）的存在。如果过滤器得到使用，独立式空气过滤器可以成为一种有效的干预措施，可大幅降低 PM 浓度。然而，过滤器的使用在整个研究人群中存在差异，并且在研究期间呈下降趋势，因此需要制定策略来鼓励和维持过滤器的使用。过滤器使用的可变性表明，在使用过滤器的干预研究中，暴露分类错误是一个潜在问题。在卧室中安装房间 AC，旨在限制空气交换率，同时安装空气过滤器，并不会比单独使用过滤器更能降低 PM 水平。
