Understudied Health Risks of High-Impact Pollution Weather: The Case for Revising Short-Term PM2.5 Standard and Indexes.

In the Anthropocene, high-impact weather (HIW) events are increasingly compressing massive air pollution loads into narrow temporal windows, posing acute health risks that conventional environmental health frameworks were not designed to capture. Despite growing recognition of these dangers, critical gaps persist in the nowcasting of atmospheric health risks, as existing tools such as the air quality index (AQI) and the global burden of disease (GBD) framework remain anchored in chronic exposure paradigms and long-term concentration averages. This manuscript focuses on a pressing standard-index paradox in China: While air quality guidelines/standards (AQG/AQS) are being tightened, the risk-communication AQIs have largely remained static, creating a widening gap in public health protection. As a pilot study, leveraging a recently developed global function between short-term PM2.5 and cardiovascular mortality (CVD), we conducted a trade-off analysis across AQI cutoff values and identified that the lower boundary for moderately polluted events yields the highest leveraging efficiency. Under the prevailing ambient AQS, the optimal warning threshold is approximately 90 μg/m³, suggesting that health-protective warnings should be extended to cover some slightly polluted days as well. These findings underscore that nowcasting the health risks of acute air pollution episodes is of substantial public health importance, and that a risk-based warning strategy should be considered to replace China's current AQI-based communication framework.