Lengthy look at what both laboratory and human studies have shown about the effectiveness of face masks. Read it and see if you still believe what you have previously been told. https://t.co/bBLli67lhT

— Brit Hume (@brithume) October 2, 2020

https://aapsonline.org/mask-facts/

Conclusion: Wearing masks (other than N95) will not be effective at preventing SARS-CoV-2 transmission, whether worn as source control or as PPE.N95s protect health care workers, but are not recommended for source control transmission.Surgical masks are better than cloth but not very efficient at preventing emissions from infected patients. Cloth masks must be 3 layers, plus adding static electricity by rubbing with rubber glove.The cloth that serves as the filtration for the mask is meant to trap particles being breathed in and out. But it also serves as a barrier to air movement because it forces the air to take the path of least resistance, resulting in the aerosols going in and out at the sides of the mask.An August 2020 UCSF study suggested that the mask would decrease the absolute volume of the inoculum. (The concentrations of bacteria upstream and downstream of the test devices were measured with an aerodynamic size spectrometer) https://ucsf.app.box.com/s/blvolkp5z0mydzd82rjks4wyleagt036