Scientist of 19 years, with 3 science degrees, has worked in the field of Occupational Environmental Toxicology as a senior industrial hygienist for almost 20 years. She has managed the respiratory protection program for over 76,000 employees. For companies in medical care, construction, you name the field, She has done it. So when the CDC says that masks do not cause bacterial infection, not only is that 1 million and 110% false, they are hiding the risks associated with mask wearing.