Air pollution and the onset of balance problems: The Canadian longitudinal study on aging.

PURPOSE: To understand the relationship between ambient air pollution and the onset of balance problems. DESIGN: Population-based prospective cohort study. METHODS: Baseline and 3-year follow-up data were used from the Canadian Longitudinal Study on Aging. The Comprehensive Cohort included adults aged 45-85 years old recruited from 11 sites across 7 provinces. Data on air pollution came from the Canadian Urban Environmental Health Research Consortium. Annual mean levels of ozone, fine particulate matter (PM2.5), and sulfur dioxide for each participant's postal code were estimated from satellite data. Balance was measured at both time points using the one-leg balance test with those who could not stand on one leg for at least 60 s defined as failing the balance test. Our outcome was the new development of failing the balance test at follow-up in those who passed the balance test at baseline. Logistic regression was used. RESULTS: Of the 12,158 people who could stand for 60 s on one leg at baseline, 18% were unable to do so 3 years later. In single pollutant models, living in an area with higher ozone levels was associated with the 3-year onset of balance problems (odds ratio (OR) = 1.13 per interquartile range of ozone, 95% CI 1.02, 1.24) after adjustment for demographic, lifestyle, and health variables. In a multipollutant model, the association with ozone increased slightly (OR = 1.16, 95% CI 1.04, 1.30). There were no associations with PM2.5 or sulfur dioxide. CONCLUSION: Our findings provide longitudinal evidence that higher ozone levels are associated with the odds of developing balance problems over a 3-year period. Further work should attempt to confirm our findings and explore the potential mechanism of action.