Fine particulate matter exposure and olfactory dysfunction among urban-dwelling older US adults

Objectives The olfactory nerve is anatomically susceptible to injury from pollution in inspired air, but there are no large-scale epidemiologic studies investigating this relationship. Methods Cross-sectional study using data from the National Social Life, Health, and Aging Project, a representative sample of home-dwelling US adults age 57–85 years. Olfactory function was tested using a validated 5-item odor identification test (Sniffin' Sticks). Exposure to fine particulate matter (PM_2.5) at each respondent's home was estimated as 1–12 month moving averages prior to olfactory assessment using validated spatio-temporal models. Results Olfactory dysfunction was significantly associated with PM_2.5 exposures averaged over 3–12 months in urban-dwelling respondents. The strongest effect was for 6 month average exposure (per 1-IQR increase in PM_2.5: OR 1.28, 95% CI 1.05, 1.55) adjusting for age, gender, race/ethnicity, education, cognition, comorbidity, smoking, and the season. Interestingly, the most deleterious effects were observed among the youngest respondents, 57–64 years old, and those living in the northeast and south. Conclusions We show for the first time that air pollution exposure is associated with poor olfaction among urban-living, older US adults.