Sand and dust storms (SDS) are a growing public health concern, contributing to poor air quality worldwide. Climate change and land use alterations have intensified their frequency and intensity. While previous studies have shown an overall association between SDS and circulatory and respiratory mortality, a comprehensive nationwide assessment of the impact on cause-specific mortality has been lacking. This gap in epidemiological evidence hinders the development of effective public health interventions. Inhalable particulate matter (PM10), a major SDS component, is well-known for its adverse health effects. However, the specific contribution of SDS, as a distinct type of PM pollution event with high concentrations of PM2.5-10 and PM2.5, to mortality remains unclear. This study aims to address these knowledge gaps by conducting a nationwide multicenter time-series analysis in China to (1) investigate the short-term effects of SDS events on mortality from a range of causes and (2) examine the added effects of SDS events on mortality, independent of general PM pollution.

Existing literature indicates an overall increase in circulatory and respiratory mortality associated with SDS events. A meta-analysis estimated a 2.33% increase in circulatory mortality and a 3.99% increase in respiratory mortality on days following SDS. However, most previous studies were limited by their small sample size and single-location focus. A national-level assessment is crucial to improve understanding and inform effective mitigation strategies. Studies have shown links between PM10 concentrations during SDS and cardiovascular mortality. While the impact of heavy PM2.5 pollution events on mortality has been explored, the specific added effects of SDS, with their unique PM composition, require further investigation. This lack of a comprehensive, nationwide assessment of SDS health impacts is a significant barrier to developing evidence-based national and regional strategies to mitigate these events and their health consequences.

This study employed a two-stage time-series analysis using daily mortality data from 2013 to 2018 for 214 Chinese counties frequently affected by SDS, covering major SDS transmission routes. Daily mortality data were obtained from China's Disease Surveillance Points System. Eighteen mortality outcomes were analyzed, including seven broad categories and eleven specific causes based on the ICD-10 classification. Daily county-specific concentrations of PM10 and PM2.5 were obtained from the National Air Pollution Monitoring System. PM2.5-10 was calculated by subtracting PM2.5 from PM10. Meteorological data (temperature and relative humidity) were sourced from the ERA5-land reanalysis dataset. SDS events were defined using official sand-dust weather records, PM10 concentration (>50 µg/m³), and the PM2.5/PM10 concentration ratio (<0.4). Generalized linear models (GLMs) with quasi-Poisson distribution were used in the first stage to assess county-level effects. A random-effects meta-analysis in the second stage yielded pooled effect estimates. Added effects of SDS were investigated by adjusting for PM2.5-10 and PM2.5 in GLMs. Lagged analyses (lags 1-3) were conducted to assess delayed effects. Sensitivity analyses were performed using alternative SDS definitions, varying degrees of freedom for spline functions, different meteorological parameter adjustments, varying study periods, and different subsets of counties.

The study found a significant increase in mortality risk associated with SDS events for various causes. Respiratory disease mortality showed the highest increase (8.90%, 95% CI: 4.96%, 12.98%) during SDS event days. Significant increases in mortality were also observed for several cause-specific outcomes, including ischemic stroke (7.49%, 95% CI: 3.12%, 12.05%), intracerebral hemorrhagic stroke (5.40%, 95% CI: 1.25%, 9.73%), hypertensive heart disease (4.05%, 95% CI: 0.41%, 7.83%), and various types of myocardial infarction and ischemic heart disease. COPD mortality showed a substantial increase (11.55%, 95% CI: 5.55%, 17.89%). Significant added effects of SDS events on mortality were observed for ischemic stroke, chronic lower respiratory disease, and COPD, even after adjusting for PM2.5 and PM2.5-10. SDS events exhibited a more pronounced impact on mortality than conventional PM pollution events for several causes. Sensitivity analyses generally supported the main findings. Stratified analyses by sex and age group did not reveal substantial differences in SDS-associated mortality risks. The strongest and most significant mortality risks were observed at lag 0 (same day as the SDS event).

This study provides strong evidence for the significant and broad impact of SDS on mortality in China. The substantial increase in respiratory mortality, particularly for COPD, highlights the vulnerability of this population group. The observed added effects of SDS on certain circulatory and respiratory outcomes, even after accounting for PM2.5 and PM2.5-10, suggest that SDS events pose unique risks beyond conventional PM pollution. The findings support the plausibility of mechanisms linking SDS exposure to cardiovascular events through systemic inflammation, oxidative stress, and vascular damage. The similar effect estimates at lag 1 suggest that immediate public health interventions are critical. The study’s large sample size and nationwide scope provide stronger evidence than previous studies which were often regionally limited. This work highlights the need for more research on the complex interplay between various PM components, SDS events, and specific health outcomes. Further research could explore the specific toxic components in SDS PM and how they might interact with existing health conditions.

This nationwide study demonstrates a significant association between short-term exposure to SDS events and increased mortality risks from various causes, especially respiratory diseases. The added effects of SDS beyond those from PM2.5 and PM2.5-10 highlight the need for targeted public health interventions. Establishing air quality guidelines specifically addressing SDS, allocating resources for vulnerable populations before SDS events, and educating the public about the health risks and protective measures are critical steps. Further research could investigate the distinct contribution of natural and anthropogenic PM sources within SDS events.

Exposure misclassification is a potential limitation due to the lack of a universally accepted SDS definition. While the study used official weather records and PM concentration data, alternative definitions were explored in sensitivity analyses. Another limitation is the limited accessibility of mortality data, preventing inclusion of all regions in China. Finally, while the study accounted for PM exposures, it could not differentiate between natural and anthropogenic sources, which warrants further investigation.