Osteoporosis is defined as a systemic skeletal disease characterized by a reduction in bone mass and microarchitectural deterioration of bone tissue. Previous studies have reported associations between air pollution and lower bone mineral density; however, few studies have investigated the association between air pollution and osteoporosis. In this study, we combined two databases, the first including 5000 individuals registered in the Taiwan Biobank, and the second containing detailed daily data on air pollution. After multivariable adjustments, ozone (O) (unstandardized coefficient β, 0.015; = 0.008) was significantly positively associated with T-score, whereas carbon monoxide (CO) (unstandardized coefficient β, -0.809; < 0.001), sulfur dioxide (SO) (unstandardized coefficient β, -0.050; = 0.005), nitric oxide (NO) (unstandardized coefficient β, -0.040; < 0.001), nitrogen dioxide (NO) (unstandardized coefficient β, -0.023; < 0.001), and nitrogen oxide (NO) (unstandardized coefficient β, -0.017; < 0.001) were significantly negatively associated with T-score. The interactions between CO and NO ( = 0.001) and SO and NO ( = 0.004) on T-score were statistically significant. An increase in exposure to CO, NO and NO was associated with a faster decline in T-score in the female participants compared to the male participants. In addition, an increase in O was associated with a faster increase in T-score in the female participants compared to the male participants. In conclusion, the air pollutants CO, SO, NO, NO, and NO were associated with osteoporosis. In addition, there were interaction and synergetic effects between CO and NO and SO and NO on T-score. We also observed differences in the associations between air pollutants and T-score between the female and male participants.