Fig. 1 Terahertz-2DCOS Analysis of PM2.5 (IMAGE) Science China Press Caption This is a terahertz-2DCOS analysis of PM2.5 during red alert period (a) and normal condition (b). 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.