As COVID-19 cases continue to plummet in the U.S., a number of mask mandates are being dropped as well. 

But the value of masks in combating virus spread has been proven over the past few years. 

So-called aerosol scientists have been in the forefront of spreading that message. 

Including one Colorado scientist who’s been very public on, where else, Twitter. 

CGTN’s Hendrik Sybrandy reports.