Climate change and anthropogenic activities are intensifying the frequency and severity of sand and dust storms (SDS), leading to higher emissions of SDS-related airborne particulate matter (dust PM). However, the health risks associated with long-term exposure to size-specific dust PM and the underlying physiological mechanisms remain unclear. We used Cox proportional hazards models to estimate the all-cause and specific-cause mortality hazard ratios (HRs) associated with long-term exposure to dust PM2.5, dust PM2.5-10 and dust PM10 in a national cohort study of 46,817 participants conducted between 2012 and 2024. And mediation analyses were performed to explore the potential mediation effects of multi-dimensional health indicators. This study had a median followup duration of 10.87 years. And the HRs for all-cause mortality were 1.060 (95% CI: 1.033-1.087), 1.039 (95% CI: 1.029-1.050), and 1.025 (95% CI: 1.017-1.033) for each 1 mu g/m3 increase in the yearly average concentration of dust PM2.5, dust PM2.5-10, and dust PM10, respectively. Increased exposure to three types of dust PM was also linked to elevated cardiovascular and respiratory mortality. Mediation analyses indicated that lung function and oxygen-carrying capacity partially mediated the associations, accounting for 5.04-26.20% of the total effect. We found that long-term dust PM exposure was significantly associated with higher all-cause and cause-specific mortality, and these effects may be mediated through lung health pathways. Targeted management to halt desertification, along with monitoring and interventions, should be strengthened to protect public health.