Background: Falls are a major cause of disability. Whether exposure to ambient air pollution contributes to the occurrence of falls remains unclear. Objective: To investigate the cross-sectional and longitudinal associations between ambient air pollution and the risk of falls in a community-dwelling adult population. Methods: We included participants aged >= 45 years from the China Health and Retirement Longitudinal Study. Ambient air pollution was quantified as city levels of PM2.5 taken from the China High-Resolution Air Pollution dataset. Self-reported falls were the outcome of interest. Using group-based trajectory modelling, falls trajectories were investigated. Multivariable-adjusted logistic regression models were used to calculate the association between PM2.5 exposure and falls. Results: A total of 9869 participants were divided into four groups according to their PM2.5 exposure: low, moderate, high, severely high. Two falls trajectories, low risk (74.3 %) and high risk (25.7 %), were observed. Exposure to moderate or high, but not severely high levels of PM2.5 elevated the risk of falls, compared with low levels of exposure cross-sectionally (Q2 (adj.OR 1.16, 95 % CI = 1.02-1.33), Q3 (adj.OR 1.29, 95 % CI = 1.13-1.47)) and longitudinally (Q3 (adj.OR 1.25, 95 % CI =1.10-1.43)). No significance for P for trend suggested non-linear associations. Females, individuals >60 years and those with cognitive impairment were observed to have a higher risk of falls from exposure to moderate to high levels of ambient air pollution, but the interaction was statistically insignificant. Conclusion: Being exposed to moderate and high PM2.5 levels was associated with an increased risk of falls among adults. The finding highlights the importance of air-quality improvement as a potential intervention to prevent falls in the community.