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

The olfactory nerve is anatomically susceptible to injury from pollution in inspired air, but there are no large-scale epidemiologic studies investigating this relationship.

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.

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.

We show for the first time that air pollution exposure is associated with poor olfaction among urban-living, older US adults.