Association between indoor formaldehyde exposure and asthma: A systematic review and meta-analysis of observational studies

摘要

About 339 million people worldwide are suffering from asthma. We aimed to investigatewhether exposure to formaldehyde (FA) is associated with asthma, which couldprovide clues for preventive and mitigation actions. This article provides a systematicreview and meta-analysis of observational studies to assess the association betweenindoor FA exposure and the risk of asthma in children and adults. An electronicsearch of PubMed, Embase, and Web of Science was performed to collect all relevantstudies published before January 1, 2020, and a total of 13 papers were included inthis meta-analysis. A random-effect model was conducted to calculate the pooledodds ratio (OR) between FA exposure and asthma. We found that each 10 μg/m~3increase in FA exposure was significantly associated with a 10% increase in the riskof asthma in children (OR = 1.10, 95% confidence interval = 1.00-1.21). We sorted theFA concentrations reported in the selected articles and categorized exposure variablesinto low (FA ≤ 22.5 μg/m~3) and high exposure (FA > 22.5 μg/m~3) according tothe median concentration of FA. In the high-exposure adult group, FA exposure mayalso be associated with an increased risk of asthma (OR = 1.81, 95% CI = 1.18-2.78).