A review of the peer-reviewed medical literature examines impacts on human health, both immunological, as well as physiological. The purpose of this video is to examine data regarding the effectiveness of facemasks, as well as safety data. The reason that both are examined in one video is that for the general public as a whole, as well as for every individual, a risk-benefit analysis is necessary to guide decisions on if and when to wear a mask.

Sources:

Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings—Personal Protective and Environmental Measures | https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article

N95 Respirators vs Medical Masks for Preventing Influenza Among Health Care Personnel | A Randomized Clinical Trial https://jamanetwork.com/journals/jama/fullarticle/2749214

RETRACTED: Facemasks in the COVID-19 era: A health hypothesis | https://www.sciencedirect.com/science/article/pii/S0306987720333028

A cluster randomised trial of cloth masks compared with medical masks in healthcare workers | https://bmjopen.bmj.com/content/bmjopen/5/4/e006577.full.pdf

[Effect of a surgical mask on six minute walking distance] https://pubmed.ncbi.nlm.nih.gov/29395560/

Effectiveness of Adding a Mask Recommendation to Other Public Health Measures to Prevent SARS-CoV-2 Infection in Danish Mask Wearers A Randomized Controlled Trial | https://www.acpjournals.org/doi/10.7326/M20-6817

Facemask against viral respiratory infections among Hajj pilgrims: A challenging cluster-randomized trial | https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0240287

Using face masks in the community: Effectiveness in reducing transmission of COVID-19 | 15 February 2021 https://www.ecdc.europa.eu/sites/default/files/documents/covid-19-face-masks-community-first-update.pdf

Masking lack of evidence with politics | July 23, 2020 | https://www.cebm.net/covid-19/masking-lack-of-evidence-with-politics/

Do physical measures such as hand-washing or wearing masks stop or slow down the spread of respiratory viruses? | https://www.cochrane.org/CD006207/ARI_do-physical-measures-such-hand-washing-or-wearing-masks-stop-or-slow-down-spread-respiratory-viruses

COMMENTARY: Masks-for-all for COVID-19 not based on sound data | https://www.cidrap.umn.edu/news-perspective/2020/04/commentary-masks-all-covid-19-not-based-sound-data

Universal Masking in Hospitals in the Covid-19 Era | https://www.nejm.org/doi/full/10.1056/NEJMp2006372

A cluster randomised trial of cloth masks compared with medical masks in healthcare workers | https://bmjopen.bmj.com/content/5/4/e006577

Mund-Nasen-Schutz in der Öffentlichkeit: Keine Hinweise für eine Wirksamkeit | https://www.thieme-connect.com/products/ejournals/pdf/10.1055/a-1174-6591.pdf

Community and Close Contact Exposures Associated with COVID-19 Among Symptomatic Adults ≥18 Years in 11 Outpatient Health Care Facilities — United States, July 2020 | https://www.cdc.gov/mmwr/volumes/69/wr/pdfs/mm6936a5-H.pdf#page=4

Experimental Assessment of Carbon Dioxide Content in Inhaled Air With or Without Face Masks in Healthy Children | A Randomized Clinical Trial | https://jamanetwork.com/journals/jamapediatrics/fullarticle/2781743