First study quoted:
DC Study: Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings—Personal Protective and Environmental Measures:
https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article?fbclid=IwAR3ASxBUrRE5LHeZsZF-iHrpTuX2PprS8FnkKGUpEUDEIAnH6s5wQOpkOJI
Second study quoted:
Nature Medicine: Respiratory virus shedding in exhaled breath and efficacy of face masks:
https://www.nature.com/articles/s41591-020-0843-2
5:22
44:21
14:23