Ambient Air Pollutants and Olfaction among Women 50–79 Years of Age from the Sister Study

BACKGROUND: Poor olfaction is common in older adults and may have profound adverse implications on their health. However, little is known about the potential environmental contributors to poor olfaction. OBJECTIVE: We investigated ambient fine particulate matter [PM [Formula: see text] in aerodynamic diameter ([Formula: see text])] and nitrogen dioxide ([Formula: see text]) in relation to poor olfaction in middle-aged to older women. METHODS: The Sister Study is a nationwide cohort of 50,884 women in the United States with annual average air pollutant exposures estimated based on participants’ residences from enrollment (2003–2009) through 2017. This analysis was limited to 3,345 women, 50–79 years of age as of January 2018, who completed the Brief Smell Identification Test (B-SIT) in 2018–2019. Poor olfaction was defined as a B-SIT score of [Formula: see text] in the primary analysis. We conducted multivariable logistic regressions, accounting for covariates and study sampling design. RESULTS: Overall, we found little evidence for associations of air pollutants with poor olfaction. The odds ratio (OR) and 95% confidence interval (CI) of poor olfaction for each interquartile range (IQR) increment of air pollutants in 2006 were 1.03 (95% CI: 0.91, 1.17) for [Formula: see text] (per [Formula: see text]) and 1.08 (95% CI: 0.96, 1.22) for [Formula: see text] (per [Formula: see text]). Results were similar in the analyses using the most recent (2017) or the cumulative average (2006–2017) air pollutant exposure data. Secondary analyses suggested potential association in certain subgroups. The OR per IQR was 1.35 (95% CI: 1.11, 1.65) for [Formula: see text] among younger participants ([Formula: see text] years of age) and 1.87 (95% CI: 1.29, 2.71) for [Formula: see text] among current smokers. DISCUSSION: This study did not find convincing evidence that air pollutants have lasting detrimental effects on the sense of smell of women 50–79 years of age. The subgroup analyses are exploratory, and the findings need independent confirmation. https://doi.org/10.1289/EHP12066