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

Abstract

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 $\le 2.5\mu m$ in aerodynamic diameter (${\mathrm{PM}}_{2.5}$)] and nitrogen dioxide (${\mathrm{NO}}_2$) 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 $\le 9$ 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 ${\mathrm{PM}}_{2.5}$ (per $3.3{\mu g/m}^3$) and 1.08 (95% CI: 0.96, 1.22) for ${\mathrm{NO}}_2$ (per $5.7\text{ppb}$). 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 ${\mathrm{PM}}_{2.5}$ among younger participants ($<54.2$ years of age) and 1.87 (95% CI: 1.29, 2.71) for ${\mathrm{NO}}_2$ 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.