Air Pollution Exposure and Olfactory Health: A Systematic Review

Abstract Exposure to air pollution can affect the olfactory system, causing disorders such as anosmia (partial or total loss of smell) and hypogeusia (reduced ability to taste). The objective of this study is to systematically review air pollution exposure and associated olfactory health disorders. The systematic review included air pollutant types, types of exposure, testing methods, and study limitations. Specific keywords related to air pollution and olfactory and/or gustatory functions were employed to search electronic databases (PubMed, Google Scholar, MEDLINE, Highwire, ResearchGate, and the Cochrane Library) for studies and reviews on exposure to air pollution that assess and measure smell and taste and published up to the year 2021. Non-English studies, studies on animals, plants, and exposure to pollutants other than air pollutants were excluded. Out of 1,100 identified studies, only 52 studies met the selection criteria. Forty-nine studies were related to olfactory health (sense of smell) associated with air pollution exposure, and three studies were related to gustatory health (sense of taste). Most studies reviewed had a small sample size and were subject to substantial confounding, making it implausible to determine a significant association between air pollution exposure and olfactory health. The review shows the study limitations and gaps that should be considered in future research related to olfactory/gustatory health and air pollution. To our knowledge, this is the first systematic review of the olfactory health studies related to air pollution exposure.