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 ≤ 2.5 μ m in aerodynamic diameter (PM 2.5 )] and nitrogen dioxide (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 ≤ 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 PM 2.5 (per 3.3   μ g / m 3 ) and 1.08 (95% CI: 0.96, 1.22) for NO 2 (per 5.7  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 PM 2.5 among younger participants (< 54.2 years of age) and 1.87 (95% CI: 1.29, 2.71) for 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.

Olfaction and Changes in Body Composition in a Large Cohort of Older U.S. Adults

BACKGROUND

Poor sense of smell in older adults may lead to weight loss, which may further contribute to various adverse health outcomes. However, empirical prospective evidence is lacking. We aimed to longitudinally assess whether poor olfaction is associated with changes in body composition among older adults.

METHODS

A total of 2,390 participants from the Health ABC Study had their olfaction assessed using the Brief Smell Identification Test in 1999-2000. Based on the test score, olfaction was defined as poor (0-8), moderate (9-10), or good (11-12). Total body mass, lean mass, and fat mass were measured by dual-energy X-ray absorptiometry annually or biennially from 1999 to 2007.

RESULTS

At baseline, compared to participants with good olfaction, those with poor olfaction weighed on average 1.67 kg less (95% CI: -2.92, -0.42) in total mass, 0.53 kg less (95% CI: -1.08, 0.02) in lean mass, and 1.14 kg less (95% CI: -1.96, -0.31) in fat mass. In longitudinal analyses, compared to participants with good olfaction, those with poor olfaction had a greater annual decline in both total mass (-234 g, 95% CI: -442, -26) and lean mass (-139 g, 95% CI: -236, -43). They also tended to have a greater annual loss of fat mass (-113 g, 95% CI: -285, 59), but the difference was not statistically significant.

CONCLUSIONS

Our results indicate poor olfaction is associated with lower body weight and greater weight loss in older adults. It is imperative for future studies to investigate potential underlying mechanisms and associated adverse health consequences.