Fig. 1 图1 (IMAGE) Science China Press Caption Terahertz-2DCOS analysis of PM2.5 during red alert period (a) and normal condition (b). 红色预警(a)和普通条件(b)下PM2.5的太赫兹-二维光谱分析结果 Credit �Science China Press Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.