Association between particulate air pollution, physical activity, and the risk of osteoporosis in the UK Biobank

As a major threat to global health, particulate air pollution has a great possibility of affecting bone metabolism. However, the results of limited studies examining the association between particulate air pollution and bone mineral density (BMD) as well as incident osteoporosis (OP) are conflicting, and the role of physical activity in the association above remains to be further studied. We evaluated the relationship between long-term exposure to Black Carbon (BC) and Particulate Matter (PM) (including PM₁ (particles with aerodynamic diameter < 1 μm), PM_2.5 (particles with aerodynamic diameter < 2.5 μm) and PM₁₀ (particles with aerodynamic diameter < 10 μm)) and BMD together with OP risks, based on a total of 233,184 subjects from the UK Biobank. General linear regression, logistic regression and restricted cubic spline (RCS) methods were adopted to measure both linear and nonlinear relationship between particulate air pollution and BMD and OP prevalence. Stratified analyses were further utilized to evaluate the potential protective effect of physical activity on bone health under particulate air pollution exposure. BC, PM₁ and PM_2.5 exposure were negatively associated with BMD (BC: β = -2.35E^-03, P = 1.78E^-02; PM₁: β = -1.57E^-03, P = 9.04E^-04; PM_2.5: β = -9.38E^-04; P = 2.98E^-13) and positively associated with OP risk (BC: OR (95 %CI) = 1.300 (1.150,1.480), P < 0.001; PM₁: OR (95 %CI) = 1.100 (1.040,1.170), P < 0.001; PM_2.5: OR (95 %CI) = 1.020 (1.000,1.040), P = 0.019). The RCS analysis presented non-linear relationships between all included particulate air pollutants and incident OP. Higher intensity physical activity could alleviate the risks of BMD decline and OP prevalence caused by particulate air pollution. Our study concluded that particulate air pollution is a crucial threat to bone health, the effect of which can be receded by physical activity. Strengthening air pollution control measures and promoting public engagement in physical activity will contribute to reducing the disease burden associated with OP.