Ambient air pollution, greenness and frailty in an elder Asian population: a multi-center study with long-term exposure

BACKGROUND: Long-term exposure to air pollution has been linked to adverse health outcomes in older adults; however, its association with frailty, particularly the potential protective role of environmental factors such as greenness, remains insufficiently investigated. METHODS: Data from the Healthy Aging Longitudinal Study in Taiwan, which included 5336 community-dwelling individuals aged 55 years and older, were analyzed. Frailty was assessed using modified criteria from the Cardiovascular Health Study. Exposure to air pollutants was estimated using land use regression model with machine learning methods. Greenness was quantified using the normalized difference vegetation index (NDVI). Logistic regression models were used to examine associations between environmental exposures and frailty after adjustment for demographic, health, and lifestyle confounders. RESULTS: Exposure to PM2.5 and NO2 during the 1-9 years preceding the assessment was significantly associated with an increased risk of frailty and prefrailty. Conversely higher NDVI values exhibited a protective effect. Mutually adjusted models confirmed the robustness of the effects of PM2.5, indicating its influence persisted for up to 3 years. The aOR for PM2.5 was 1.103 per 10 µg/m³ increment for 3 year prior to the assessment, corresponding to an excess risk of 10.3% per 10 µg/m³ increase. CONCLUSIONS: Long-term exposure to PM2.5 related to frailty in older adults, whereas greenness provides protective benefits. These findings indicate the importance of developing public health policies aimed at improving air quality and promoting greening in ensuring healthy aging.