Long-term ultrafine particles exposure and prevalence of cardiovascular diseases and stroke: The 33-communities Chinese health study

Evidence on ultrafine particles (UFP) and cardiovascular health in developing countries remains limited. This study investigated associations between long-term UFP exposure and cardiovascular diseases (CVD) and stroke among 24,845 adults from the 33-Communities Chinese Health Study, comparing the effects with those of particulate matter of aerodynamic diameter ≤ 1 μm (PM₁), ≤ 2.5 μm (PM_2.5), and ≤ 10 μm (PM₁₀). Four-year average UFP (mass and number), PM₁, PM_2.5, and PM₁₀ concentrations were estimated using Weather Research Forecasting model coupled with Chemistry (WRF-Chem) and spatiotemporal model, respectively. Each interquartile range increase in UFP mass concentration was associated with significantly higher prevalence of CVD (OR=1.99, 95 % CI: 1.66–2.39) and stroke (OR=1.63, 95 % CI: 1.31–2.02), while number concentration was associated only with CVD (OR=1.38, 95 % CI: 1.18–1.62). UFP mass exhibited stronger effects than PM₁ (OR=1.31 for CVD; 1.12 for stroke), PM_2.5 (OR=1.29 for CVD; 1.12 for stroke), and PM₁₀ (OR=1.18 for CVD; 1.38 for stroke). Stratified analysis indicated elevated risks among highly educated and regularly exercising individuals. This large-scale study in a high-exposure Chinese population provides evidence that UFP poses greater cardiovascular risks than larger particles, demonstrates stronger effects for mass versus number concentration, and underscores the necessity of incorporating UFP into air quality monitoring.