Formaldehyde exposure and asthma in children: a systematic review.
ABSTRACT Despite multiple published studies regarding the association between formaldehyde exposure and childhood asthma, a consistent association has not been identified. Here we report the results of a systematic review of published literature in order to provide a more comprehensive picture of this relationship. After a literature search, we identified seven studies providing quantitative results regarding the association between formaldehyde exposure and asthma in children. Studies were heterogeneous with respect to the definition of asthma. For each study, an odds ratio (OR) and 95% confidence interval (CI) for asthma were abstracted from published results or calculated based on the data provided. We used fixed- and random-effects models to calculate pooled ORs and 95% CIs; measures of heterogeneity were also calculated. A fixed-effects model produced an OR of 1.03 (95% CI, 1.021.04), and random effects model produced an OR of 1.17 (95% CI, 1.011.36), both reflecting an increase of 10 mg/m3 of formaldehyde. Both the Q and I2 statistics indicated a moderate amount of heterogeneity. Results indicate a positive association between formaldehyde exposure and childhood asthma. Given the largely cross-sectional nature of the studies underlying this meta-analysis, further well-designed prospective epidemiologic studies are needed.
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Conference Paper: Asthmagens in Building Materials: The Problem and Solutions[Show abstract] [Hide abstract]
ABSTRACT: Asthma is a complex, heterogeneous disease, often of multifactorial origin. Asthma rates in the USA have been rising since at least 1980. These rates are rising despite the proliferation of asthma control strategies, including indoor air quality programs. The Centers for Disease Control (CDC) reported that the number of people diagnosed with asthma grew by 4.3 million during the last decade. Nearly 26 million people are affected by chronic asthma, including over eight million children. As asthma affects more people, new strategies need to be considered. Among asthma risk factors, health organizations have identified hundreds of substances that can cause the onset of asthma. Many of these asthmagens are common ingredients of building products like insulation, paints, adhesives, wall panels and floors. This paper identifies asthmagens found in building products, how people can be exposed to these substances, and what is known and yet- to-be known about the impacts of these exposures. Key strategies to minimize exposures to asthmagens in building materials include understanding the composition of building materials; using product ingredient disclosure tools such as those recognized in LEED v4; and, modifying product certification standards, restricted substance lists, indoor environmental testing protocols, and green building incentives.Greenbuild 2014, New Orleans; 10/2014
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ABSTRACT: Measurements were taken in new US residences to assess the extent to which ventilation and source control can mitigate formaldehyde exposure. Increasing ventilation consistently lowered indoor formaldehyde concentrations. However, at a reference air exchange rate of 0.35 h−1, increasing ventilation was up to 60% less effective than would be predicted if the emission rate were constant. This is consistent with formaldehyde emission rates decreasing as air concentrations increase, as observed in chamber studies. In contrast, measurements suggest acetaldehyde emission was independent of ventilation rate. To evaluate the effectiveness of source control, formaldehyde concentrations were measured in Leadership in Energy and Environmental Design (LEED) certified/Indoor airPLUS homes constructed with materials certified to have low emission rates of volatile organic compounds (VOC). At a reference air exchange rate of 0.35 h−1, and adjusting for home age, temperature and relative humidity, formaldehyde concentrations in homes built with low-VOC materials were 42% lower on average than in reference new homes with conventional building materials. Without adjustment, concentrations were 27% lower in the low-VOC homes. The mean and standard deviation of formaldehyde concentration were 33 μg m−3 and 22 μg m−3 for low-VOC homes and 45 μg m−3 and 30 μg m−3 for conventional.This article is protected by copyright. All rights reserved.Indoor Air 09/2014; DOI:10.1111/ina.12160 · 4.20 Impact Factor
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ABSTRACT: The rotary enthalpy wheel design used in many energy recovery ventilators (ERVs) is designed to transfer heat and moisture between supply and exhaust air streams. The wheel, however, can also transfer formaldehyde and other indoor contaminants from the exhaust stream to the supply stream through air leakage, entrainment in the porous wheel, and adsorption/desorption to the filter medium. This contaminant transfer reduces the benefit of the mechanical ventilation provided by the device. Field and chamber experiments were used to quantify the formaldehyde transfer efficacy (the fraction of formaldehyde transferred from the exhaust stream to the supply stream) in a common ERV model under varied conditions. In field experiments, the transfer efficacy was approximately 29%. Chamber tests showed formaldehyde transfer efficacy between 10 and 29%. The bulk of the transfer was due to air leakage and entrainment within the wheel, with up to 30% of the transfer attributed adsorption/desorption from the filter medium. The transfer efficacy decreased with increasing air exchange rate and supply air temperature. The transfer efficacy increased as the supply and exhaust streams were unbalanced in flow rate. Overall, the air leakage through the device substantially exceeded the product rating of 10%, with 27–28% air leakage measured in field experiments and 12–19% air leakage in chamber experiments.Building and Environment 05/2014; 75:92–97. DOI:10.1016/j.buildenv.2014.01.004 · 2.70 Impact Factor