Thanks, Doc B., all good stuff.
Here is one article I picked up from the JAMA Network. This article addressed an issue I personally have with wearing a mask for prolonged time periods. For me, that period is around ten minutes before feeling the effects. Sorry for not posting a link but I could not generate one as it was part of several other articles.
April 18, 2020
Potential Risks When Some Special People Wear Masks
Zheng Zhaoshi, PH.D. M.D. | No. 1 Department of Neurology, The Third Hospital of Jilin University
As more asymptomatic patients with SARS-CoV-2 infection are found in the world, wearing N95 masks is undoubtedly an effective respiratory protective measure (1). However, wearing an N95 mask for a long time may bring potential risks and even complications that are difficult to eliminate.
Oxygen concentration inhaled by healthy subjects wearing a surgical mask covering an N95 respirator decreases to about 17%, and the concentration of carbon dioxide increases to about 1.2% - 3% in a short period of light work (2-3). Although participants did not show any obvious changes in physical function and did not have any discomfort ratings, the average carbon dioxide concentration inhaled was far higher than the limit of 0.1% of indoor carbon dioxide concentration in many countries. With prolonged mask wearing, untoward reactions may gradually appear. In another long-term study, after wearing an N95 mask for 12 hours the CO2 concentration of subjects increased to 41.0 mmHg, far higher than the baseline value of 32.4mm Hg at the beginning of the test (4). The subjects mainly reported headache, dizziness, feeling tired and communication obstacles. In real life, the situations and time of wearing masks are much longer than the above experimental research settings.
Therefore, when taking strong measures to prevent and control COVID-19 we should also pay attention to implementation of individualized strategies. Pregnant women and patients with basic respiratory diseases are the most vulnerable groups. These high-risk groups should try to choose a way of isolation away from others. Many kindergartens and middle schools in many provinces of China have begun to resume classes or plan to resume classes in the near future. Most of them require students to wear masks during the school period. It is questionable that students wear masks for a long time, especially for the children in low school years.
We declare no conflict of interest.
Reference
1. Offeddu V, Yung C F, Low M S, et al.Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis.Clinical Infectious Diseases, 2017, 65(11): 1934-1942. doi: 10.1093/cid/cix681
2. Roberge R J, Coca A, Williams W J, et al. Surgical mask placement over N95 filtering facepiece respirators: physiological effects on healthcare workers[J]. Respirology, 2010, 15(3): 516-521. doi:10.1111/j.1440-1843.2010.01713.x
3. Sinkule E J, Powell J B, Goss F L, et al.Evaluation of N95 Respirator Use with a Surgical Mask Cover: Effects on Breathing Resistance and Inhaled Carbon Dioxide.Annals of Occupational Hygiene, 2013, 57(3): 384-398. doi:10.1093/annhyg/mes068
4. Rebmann T, Carrico R, Wang J, et al.Physiologic and other effects and compliance with long-term respirator use among medical intensive care unit nurses. American Journal of Infection Control, 2013, 41(12): 1218-1223. doi:10.1016/j.ajic.2013.02.017.