BackgroundThe air pollution caused by vehicular emissions is associated with cognitive decline. However, the associations between the levels of nitrogen dioxide (NO2) and carbon monoxide (CO) exposure and dementia remain poorly defined and have been addressed in only a few previous studies.Materials and MethodsIn this study, we obtained data on 29547 people from the National Health Insurance Research Database (NHIRD) of Taiwan, including data on 1720 patients diagnosed with dementia between 2000 and 2010, and we evaluated the risk of dementia among four levels of air pollutant. Detailed data on daily air pollution were available from January 1, 1998 to December 31, 2010. Yearly average concentrations of pollutants were calculated from the baseline to the date of dementia occurrence, withdrawal of patients, or the end of the study, and these data were categorized into quartiles, with Q1 being the lowest level and Q4 being the highest.ResultsIn the case of NO2, the adjusted hazard ratios (HRs) of dementia for all participants in Q2, Q3, and Q4 compared to Q1 were 1.10 (95% confidence interval (CI), 0.96–1.26), 1.01 (95% CI, 0.87–1.17), and 1.54 (95% CI, 1.34–1.77), and in the case of CO, the adjusted HRs were 1.07 (95% CI, 0.92–1.25), 1.37 (95% CI, 1.19–1.58), and 1.61 (95% CI, 1.39–1.85).ConclusionThe results of this large retrospective, population-based study indicate that exposure to NO2 and CO is associated with an increased risk of dementia in the Taiwanese population.

The aim of this study was to investigate whether ambient nitrogen dioxide (NO2) and carbon monoxide (CO) increase the risk for age-related macular degeneration (AMD). This is a longitudinal population-based study using the data on Taiwan National Health Insurance Program between year 2000 and 2010. From the nationwide dataset, we enrolled subjects aged 50 or older and the annually total NO2 and CO exposure was calculated from 1998 to 2010 for each subject. The Cox proportional hazard regression was used to estimate the HRs with adjustment for other variables. A total of 39,819 AMD-free residents were enrolled, and 1442 participants developed AMD during the 11 -year follow-up. Compared with the lowest exposure quartile, the highest quartile of each air pollutant was associated with an increased risk for AMD. The adjusted HR was 1.91 (95% CI 1.64 to 2.23, p<0.001) for the highest NO2 quartile, and was 1.84 (95% CI 1.5 to 2.15, p<0.001) for the highest CO quartile. In this study, chronic exposure to the highest quartile of ambient NO2 or CO significantly increases the risk for AMD.