Low temperatures are an important risk factor for chronic obstructive pulmonary disease (COPD). However, trends and projections of the global burden of COPD at low temperatures are unclear. Based on data from the 2021 Global Burden of Disease Study (GBD), this study assessed trends in the global and regional burden of death and disability-adjusted life years (DALYs) due to COPD from 1990 to 2021, and identified patterns of change in different regions. A Bayesian Age-Period-cohort (BAPC) model was used to predict the burden of COPD over the next 20 years. Although the number of COPD deaths worldwide in 2021 increased from 242,170 in 1990 to 300,849, and the number of DALYs increased from 4,749,734 to 4,981,981, the age-standardized deaths rate decreased from 7.04 to 3.69 per 100,000, and the DALYs rate decreased from 126.69 to 59.22 per 100,000. Up to 2021, men consistently bore a higher burden than women, though their age-standardized deaths rate declined more sharply (54.2% vs. 39.2%). COPD burden increased notably after age 45, with those aged 65 and older contributing most to the total and showing the steepest rise. By SDI level, middle and middle-high SDI regions had the highest burden but saw the fastest declines, while low and low-middle SDI areas carried heavier burdens with slower reductions. High SDI regions maintained low and stable burden levels. BAPC projections suggest a continued but slower decline in COPD mortality linked to low temperature by 2041, with a projected drop of 1.39 per 100,000, less than the 3.35 per 100,000 reduction observed from 1990 to 2021. Global age-standardized mortality and DALYs for COPD at risk of low temperatures have declined over the past 30 years, with absolute burden numbers, BAPC predicting a slower rate of decline in the future, and persistent cross-country health inequalities. More precise interventions should be developed to target the resistance to low-temperature risk in older age groups and areas with low SDI.

Background: The timeliness of treatment for out-of-hospital cardiac arrest (OHCA) is critical for patient survival. Automated External Defibrillators (AEDs) are a proven effective intervention, yet China’s rapidly developing Public Access Defibrillation (PAD) program may be accompanied by significant spatial inequities in AED distribution. Methods: This study developed a comprehensive multi-dimensional evaluation model to assess the spatial equity of AED allocation in four first-tier Chinese cities: Beijing, Shanghai, Guangzhou, and Shenzhen. The model integrated four dimensions: resource allocation (supply–demand ratio), spatial coverage (service coverage index), opportunity accessibility (accessibility index via an enhanced Gaussian two-step floating catchment area method), and spatial distribution (Gini coefficient). These dimensions were aggregated into a Comprehensive Equity Index (CEI) using the Entropy Weight Method (EWM). Leveraging high-resolution gridded population data and precise AED locations, our analysis captures fine-scale spatial variations often obscured in aggregate statistics. Furthermore, to uncover the spatially heterogeneous drivers of equity, we employed an integrated Principal Component Analysis and Geographically Weighted Regression (PCA-GWR) framework to analyze socioeconomic and urban environmental factors. Results: The results indicate that: (1) Overall comprehensive equity was low across all cities (mean CEI < 0.3). Shenzhen exhibited the highest equity (mean CEI: 0.252), followed by Beijing (0.207), with Shanghai and Guangzhou lagging. (2) A significant “core-periphery” disparity was observed in all cities, with core districts showing markedly higher equity than suburban districts, a gap particularly pronounced in Beijing and Shanghai. (3) The PCA-GWR analysis revealed pronounced spatial heterogeneity in the associations between external factors and AED equity. Degree of urbanization showed a generally positive association, which was consistently weaker in urban cores. Public service facility provision exhibited inconsistent (often negative) associations, while the wealth-population density trade-off demonstrated marked city-specific variation. Conclusions: This study provides a systematic, multidimensional assessment of AED allocation equity in major Chinese cities. By employing a spatially nuanced PCA-GWR framework, it reveals that equity is shaped by complex, location-specific interactions of urban development, service provision, and socioeconomic structure. The findings underscore the necessity for spatially differentiated policy interventions within China’s PAD program to achieve more equitable and efficient deployment of these lifesaving resources.