Association between odour pollution from industrial sources and human health: a systematic review and meta-analysis

Objective: To conduct a systematic review to evaluate the association between residential or occupational short- and long–term exposure to odour pollution from industrial sources and the health status of the exposed population. Methods: The searches were conducted in Medline, EMBASE and Scopus in October 2018. Exposure to an environmental odour from industrial sources in the residential and occupational sector resident population or in workers was considered. Outcomes for which there was a biological plausibility, such as wheezing and asthma, cough, headache, nausea and vomiting, annoyance (primary outcomes), were considered. Stress-related symptoms and novel outcomes (e.g. mood states) were also included. Risk of bias was evaluated using the OHAT tool. For primary outcomes, when at least 3 studies provided effect estimates by comparing exposed subjects versus not exposed, the study-specific estimates of odour-related effect were pooled using random effects models. Heterogeneity was evaluated with Higgins I2. Results: Twenty-nine studies were eligible for this review, mainly cross-sectional(n=23). Only one study involved school-age children and two studies involved workers. Only four studies reported odour effects on objective laboratory or clinical outcomes. Animal Feeding Operations and waste were the most common industrial sources. The overall odds ratios in exposed versus not exposed population were 1.15 (95% CI 1.01 to 1.29) for headache (7 studies), 1.09 (95% CI 0.88 to 1.30) for nausea/vomiting (7 studies), and 1.27 (95% CI 1.10 to 1.44) for cough/phlegm (5 studies). Heterogeneity was a moderate concern. Overall, the body of evidence was affected by a definitely high risk of bias in exposure and outcome assessment since most studies used self-reported information. Conclusions: Findings underline the public health importance of odour pollution for population living nearby industrial odour sources. The limited evidence for most outcomes supports the need for high quality epidemiological studies on the association between odour pollution and its effects on human health.