Olfactory dysfunction has profound effects on quality of life, physical and social function, and mortality itself. Nitrogen dioxide (NO 2) is a pervasive air pollutant that is associated with respiratory diseases. Given the olfactory nerve’s anatomic exposure to airborne pollutants, we investigated the relationship between NO 2 exposure and olfactory dysfunction.
The ability to identify odors was evaluated using a validated test in respondents from the National Social Life, Health, and Aging Project (NSHAP), a representative probability sample of home-dwelling, older US adults ages 57–85. Exposure to NO 2 pollution was assessed using measurements obtained from the US EPA AIRS ambient monitoring site closest to each respondent’s home. We tested the association between NO 2 exposure and olfactory dysfunction using multivariate logistic regression.
Among older adults in the US, 22.6% had impaired olfactory function, defined as ≤ 3 correct (out of 5) on the odor identification test. Median NO 2 exposure during the 365 days prior to the interview date was 14.7 ppb (interquartile range [IQR] 10.8–19.7 ppb). An IQR increase in NO 2 exposure was associated with increased odds of olfactory dysfunction (OR 1.35, 95% CI: 1.07–1.72), adjusting for age, gender, race/ethnicity, education, cognition, comorbidity, smoking, and season of the home interview (n=1,823).