This video, allegedly made by a science teacher, shows how massive is the level of Carbon dioxide (CO2) that we breathe back when wearing a face mask.

0~1000 parts/million = safe
~2000/million = problematic
3000/million ~ = toxicity

Even with the mask not completely sealed the meter still reads values above 10000 parts per million.

The video was promptly taken down from YouTube by its AI censorship software (hence the double irony used by the person in the video). A few links are still working today (hence me mirroring it for safe keeping).

For those who still think that apart from increasing CO2 toxicity and contextually reduce O2 intake, face masks do actually play any significant role in reducing the transmission of airborne viruses here are some academic and medical studies that prove the contrary:

⁣https://www.cambridge.org/core/journals/epidemiology-and-infection/article/face-masks-to-prevent-transmission-of-influenza-virus-a-systematic-review/64D368496EBDE0AFCC6639CCC9D8BC05


⁣https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1750-2659.2011.00307.x


⁣https://www.ncbi.nlm.nih.gov/pubmed/19216002

⁣https://doi.org/10.1093/cid/cix681

⁣https://academic.oup.com/cid/article/65/11/1934/4068747



And no, not even the N95 would do any difference


⁣https://www.cmaj.ca/content/188/8/567
“We identified 6 clinical studies … In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection, (b) influenza-like illness, or (c) reported work-place absenteeism.” 3


⁣https://jamanetwork.com/journals/jama/fullarticle/2749214
“Among 2862 randomized participants, 2371 completed the study and accounted for 5180 HCW-seasons. … Among outpatient health care personnel, N95 respirators vs medical masks as worn by participants in this trial resulted in no significant difference in the incidence of laboratory-confirmed influenza.”

⁣https://doi.org/10.1111/jebm.12381

⁣https://onlinelibrary.wiley.com/doi/epdf/10.1111/jebm.12381
⁣“A total of six RCTs involving 9 171 participants were included. There were no statistically significant differences in preventing laboratory‐confirmed influenza, laboratory‐confirmed respiratory viral infections, laboratory‐confirmed respiratory infection and influenza-like illness using N95 respirators and surgical masks. Meta‐analysis indicated a protective effect of N95 respirators against laboratory‐confirmed bacterial colonization (RR = 0.58, 95% CI 0.43‐0.78). The 4 use of N95 respirators compared with surgical masks is not associated with a lower risk of laboratory‐confirmed influenza.”