Some physicians and researchers have raised a concern about the chronic use of N95 masks in populations for long periods of time. This is a controversial subject as there are no randomized, controlled studies looking at the association between well-fitting, long-term N95 mask use, and increased future dementia risk. Most pulmonologists do not think regular masks decrease oxygen and will not cause long term risks: https://wexnermedical.osu.edu/blog/masks-oxygen-levels

Still, with so many using masks now for many hours a day, particularly children, some doctors do have concerns about non-95 masks as well. The issue is that studies may take years to determine the long-term effect of even mild increases in ambient CO2 levels within masks and the relative decrease in oxygen. For young brains, could this increase dementia risks in the future? It is not clear but a concern.

A properly fitting N95 mask may decrease respiratory oxygen significantly in certain patients (see this reference: Ref 1: https://pubmed.ncbi.nlm.nih.gov/20420727/). In this study, the authors note that breathing environment CO2 >3% has been associated with detrimental physiological effects (Ref: 2) and prolonged breathing CO2 at greater than atmospheric levels can cause symptoms of headaches, anxiety, confusion, and other stresses on the body as it tries to compensate. In their charts, they note that the dead space’s (ie the space one re-breathes in the mask) CO2 of the N95 mask (ie, filtering facepiece respirator FFR) was 3.0-3.5 depending on the time measured after exercise and type of N95 (ie with or without a filter). The authors conclude that further studies are needed as they only had 10 patients (healthy adults) in their study.

In order to really prevent COVID in close contact situations, data has suggested that you need a properly fitted N95. Johns Hopkins asks us, surgeons, to be fitted properly which means it really fits snug on the face.

Some more recent studies say there is no decrease in oxygen saturation in patients who use N95 masks. There are confounders in many studies: such as, the size of the study, how long did they have the mask on? What is the kidney function? What type of activity/exercise was done wile this is being evaluated? Was the patient pregnant?

Reference 4 below shows there is an effect of a properly fitted N95 mask on a pregnant woman’s O2 and CO2 level. Some of the articles below that older patients and those on dialysis or those already with dementia have a higher risk of worsening dementia with decreasing O2 intake and increasing CO2 intake. It is likely that a patient’s oxygen intake may be negatively affected by tighter/snugger N95 masks used for long periods of time.

It is also well known that decreased oxygen levels for hours increase the risk of dementia. (Ref 1, 2 below):**

Which will be deemed worse in the end: COVID 19 and the potential risk of death OR the potential long-term increased risk of dementia with a slower, potentially more difficult situation for our loved ones? This is a tough issue for all of us.

More data is needed to prove this hypothesis. The fact is that we do NOT know the effect of chronic mask use (ie 4-6hrs per day for days at a time) on kids. There is a potential risk we will not fully understand the negative effects of masks for years to come.

In the meantime, most of my colleagues do not use an N95 mask: one of my fellow surgeons became light-headed and got a headache on the first day of use. We all now generally use surgical masks unless we know we will be exposed to a COVID positive patient.

We all try to take the mask off to breathe as often as possible.

And I will be increasing my vitamin B6, B12, folate https://www.healthline.com/nutrition/folic-acid-vs-folate#folic-acid, and choline intake as it appears to have a neuroprotective effect on the brain against hypoxia taking more multivitamins as study below suggests. I am waiting for the full paper below from Johns Hopkins to see how many milligrams they used.

Below are examples of ones I ordered or will order.
Just make sure none of the ones you use have partially hydrogenated vegetable oil. I do not not think any of these do. Surprisingly, many multivitamins have this.

https://www.fbs-wp.leeds.ac.uk/blogs/dementia/resource-map/role-of-hypoxia-in-developing-alzheimers-disease-can-we-protect-the-brain/#comment-2509

https://www.fbs-wp.leeds.ac.uk/blogs/dementia/resource-map/impaired-oxygen-increase-risk-of-alzheimers/

Thank Prof Chris Peers & Dr Natalia Nalivaeva:

Questions I sent them and am waiting a reply: do you think long term use of N95 masks will increase risk of dementia down the line? From a perspective of dementia progression: would you agree that it is not ideal for patients with dementia to use an N95 mask long term as these masks decrease oxygen to the brain?

Scheme of effect of hypoxia on the brain

**References:

1. Respir Care 2010 May;55(5):569-77.

Physiological impact of the N95 filtering facepiece respirator on healthcare workers

Raymond J Roberge 1, Aitor Coca, W Jon Williams, Jeffrey B Powell, Andrew J Palmiero

Abstract

OBJECTIVE: To assess the physiological impact of the N95 filtering facepiece respirator (FFR) on healthcare workers.

METHODS: Ten healthcare workers each conducted multiple 1-hour treadmill walking sessions, at 1.7 miles/h, and at 2.5 miles/h, while wearing FFR with exhalation valve, FFR without exhalation valve, and without FFR (control session). We monitored heart rate, respiratory rate, tidal volume, minute volume, blood oxygen saturation, and transcutaneously measured PCO2. We also measured user comfort and exertion, FFR moisture retention, and the carbon dioxide and oxygen concentrations in the FFR’s dead space.

RESULTS: There were no significant differences between FFR and control in the physiological variables, exertion scores, or comfort scores. There was no significant difference in moisture retention between FFR with and without exhalation valve. Two subjects had peak PCO2 ≥ 50 mm Hg. The FFR with exhalation valve offered no benefit in physiological burden over the FFR without valve. The FFR dead-space oxygen and carbon dioxide levels did not meet the Occupational Safety and Health Administration’s ambient workplace standards.

CONCLUSIONS: In healthy healthcare workers, FFR did not impose any important physiological burden during 1 hour of use, at realistic clinical work rates, but the FFR dead-space carbon dioxide and oxygen levels were significantly above and below, respectively, the ambient workplace standards, and elevated PCO2 is a possibility. Exhalation valve did not significantly ameliorate the FFR’s PCO2 impact.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6535079/

Cerebral hypoxia, via both genetic and epigenetic mechanisms, increase amyloid-β deposition by altering expression levels of enzymes involved in the production/degradation of the protein. Furthermore, hypoxia has also been linked to neuronal and glial-cell calcium dysregulation through formation of calcium-permeable pores, dysregulated glutamate signaling, and intracellular calcium-store dysfunction. Hypoxia has also been strongly linked to neuroinflammationNeuroinflammation is a key consequence of cerebral hypoxia, and has also been linked to AD pathogenesis. Here, we discuss evidence that cerebral hypoxia can lead to chronic activation and recruitment of proinflammatory immune cells, with particular focus on microglia.

2. Harber P, Beck J, Brown C, Luo J. Physiologic and subjective effects of respirator mask type. Am Ind Hyg Assoc J 1991;52(9):357-362

3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3776495/

4.THIS ARTICLE HAS BEEN CORRECTED.

See Antimicrob Resist Infect Control. 2016 July 4; 5: 26.

Respiratory consequences of N95-type Mask usage in pregnant healthcare workers—a controlled clinical study

Pearl Shuang Ye Tong, Anita Sugam Kale, […], and Eu-Leong Yong

Additional article information

Abstract

Background

Outbreaks of emerging infectious diseases have led to guidelines recommending the routine use of N95 respirators for healthcare workers, many of whom are women of childbearing age. The respiratory effects of prolonged respirator use on pregnant women are unclear although there has been no definite evidence of harm from past use.

Methods

We conducted a two-phase controlled clinical study on healthy pregnant women between 27 to 32 weeks gestation. In phase I, energy expenditure corresponding to the workload of routine nursing tasks was determined. In phase II, pulmonary function of 20 subjects was measured whilst at rest and exercising to the predetermined workload while breathing ambient air first, then breathing through N95-mask materials.

Results

Exercising at 3 MET while breathing through N95-mask materials reduced mean tidal volume (TV) by 23.0 % (95 % CI −33.5 % to −10.5 %, p < 0.001) and lowered minute ventilation (VE) by 25.8 % (95 % CI −34.2 % to −15.8 %, p < 0.001), with no significant change in breathing frequency compared to breathing ambient air. Volumes of oxygen consumption (VO2) and carbon dioxide expired (VCO2) were also significantly reduced; VO2 by 13.8 % (95 % CI −24.2 % to −3 %, p = 0.013) and VCO2 by 17.7 %, (95 % CI −28.1 % to −8.6 %, p = 0.001). Although no changes in the inspired oxygen and carbon dioxide concentrations were demonstrated, breathing through N95-mask materials during low intensity work (3 MET) reduced expired oxygen concentration by 3.2 % (95 % CI: −4.1 % to −2.2 %, p < 0.001), and increased expired carbon dioxide by 8.9 % (95 % CI: 6.9 % to 13.1 %; p <0.001) suggesting an increase in metabolism. There were however no changes in the maternal and fetal heart rates, finger-tip capillary lactate levels and oxygen saturation and rating of perceived exertion at the work intensity investigated.

Conclusions

Breathing through N95 mask materials have been shown to impede gaseous exchange and impose an additional workload on the metabolic system of pregnant healthcare workers, and this needs to be taken into consideration in guidelines for respirator use. The benefits of using N95 mask to prevent serious emerging infectious diseases should be weighed against potential respiratory consequences associated with extended N95 respirator usage.

5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6535079/

6. https://www.pnas.org/content/103/49/18727/tab-article-info

7. Karnauskas, K. B., et al. (2020) Fossil fuel combustion is driving indoor CO2 toward levels harmful to human cognition. GeoHealth. doi.org/10.1029/2019GH000237.

https://www.news-medical.net/news/20200421/Atmospheric-CO2-levels-can-cause-cognitive-impairment.aspx

8. https://academic.oup.com/annweh/article/57/3/384/230992

The recognizable effect of inhaled CO₂ is the stimulating action upon respiration, i.e. respiratory removal of CO₂ occurs through the increase in ventilation rate. Respiratory rate, tidal volume, and alveolar CO₂ become elevated with inhaled CO₂ concentrations above ambient (Schneider and Truesdale, 1922; Consolazio et al., 1947; Patterson et al., 1955). These physiological responses occur to compensate for abnormal diffusion of CO₂ from the blood, due to a decrease in the ratio of alveolar to capillary CO₂ (Schulte, 1964). In addition to the increased rate and depth of breathing, cardiac output will increase to compensate for the additional CO₂ (Schulte, 1964). While inhaling 1–2% CO₂ for 17–32min, slight increases have been reported in systolic and diastolic blood pressures (Schneider and Truesdale, 1922). Exposures of increased inhaled CO₂ between 2 and 3% have been known to produce sweating, headache, and dyspnea for some subjects at rest after several hours (Schneider and Truesdale, 1922). If inhaled CO₂ concentrations are between 4 and 5%, dyspnea can occur within several minutes and increased blood pressure, dizziness, and headache can occur within 15–32min (Schneider and Truesdale, 1922; Patterson et al., 1955; Schulte, 1964). If inhaled CO₂ exposures are at 5%, mental depression may occur within several hours (Consolazio et al., 1947; Schulte, 1964). As noted in several of these studies, headaches have been reported at inhaled CO₂ concentrations similar to those found in this investigation. This is consistent with one study which found that 37% of healthcare workers surveyed reported headaches following FFR use (Lim et al., 2006).

Tong et al. Antimicrobial Resistance and Infection Control (2015) 4:48
DOI 10.1186/s13756-015-0086-z

Respiratory consequences of N95-type
Mask usage in pregnant healthcare
workers—a controlled clinical study
Pearl Shuang Ye Tong1
, Anita Sugam Kale1
, Kailyn Ng1
, Amelia Peiwen Loke1
, Mahesh Arjandas Choolani1
,
Chin Leong Lim2
, Yiong Huak Chan3
, Yap Seng Chong1
, Paul Anantharajah Tambyah4 and Eu-Leong Yong4*
Abstract
Background: Outbreaks of emerging infectious diseases have led to guidelines recommending the routine use of
N95 respirators for healthcare workers, many of whom are women of childbearing age. The respiratory effects of
prolonged respirator use on pregnant women are unclear although there has been no definite evidence of harm
from past use.
Methods: We conducted a two-phase controlled clinical study on healthy pregnant women between 27 to 32
weeks gestation. In phase I, energy expenditure corresponding to the workload of routine nursing tasks was
determined. In phase II, pulmonary function of 20 subjects was measured whilst at rest and exercising to the
predetermined workload while breathing ambient air first, then breathing through N95-mask materials.
Results: Exercising at 3 MET while breathing through N95-mask materials reduced mean tidal volume (TV) by
23.0 % (95 % CI −33.5 % to −10.5 %, p < 0.001) and lowered minute ventilation (VE) by 25.8 % (95 % CI −34.2 %
to −15.8 %, p < 0.001), with no significant change in breathing frequency compared to breathing ambient air. Volumes
of oxygen consumption (VO2) and carbon dioxide expired (VCO2) were also significantly reduced; VO2 by 13.8 % (95 %
CI −24.2 % to −3 %, p = 0.013) and VCO2 by 17.7 %, (95 % CI −28.1 % to −8.6 %, p = 0.001). Although no changes in the
inspired oxygen and carbon dioxide concentrations were demonstrated, breathing through N95-mask materials
during low intensity work (3 MET) reduced expired oxygen concentration by 3.2 % (95 % CI: −4.1 % to
−2.2 %, p < 0.001), and increased expired carbon dioxide by 8.9 % (95 % CI: 6.9 % to 13.1 %; p <0.001) suggesting an
increase in metabolism. There were however no changes in the maternal and fetal heart rates, finger-tip capillary
lactate levels and oxygen saturation and rating of perceived exertion at the work intensity investigated.
Conclusions: Breathing through N95 mask materials have been shown to impede gaseous exchange and impose an
additional workload on the metabolic system of pregnant healthcare workers, and this needs to be taken into
consideration in guidelines for respirator use. The benefits of using N95 mask to prevent serious emerging
infectious diseases should be weighed against potential respiratory consequences associated with extended
N95 respirator usage.
Trial Registration: The study was registered at clinicaltrials.gov, identifier NCT00265926.
Keywords: N95 resp

10. J Formos Med Assoc

. 2004 Aug;103(8):624-8.

The physiological impact of wearing an N95 mask during hemodialysis as a precaution against SARS in patients with end-stage renal disease

Tze-Wah Kao 1, Kuo-Chiang Huang, Yu-Ling Huang, Tun-Jun Tsai, Bor-Shen Hsieh, Ming-Shiou Wu

Affiliations

PMID: 15340662

Abstract

Background and purpose: Most patients with end-stage renal disease (ERSD) visiting our hospital for hemodialysis treatment during the SARS outbreak wore an N95 mask. Data on the physiological stress imposed by the wearing of N95 masks remains limited. This study investigated the physiological impact of wearing an N95 mask during hemodialysis (HD) on patients with ESRD.

Methods: ESRD patients who received regular HD at National Taiwan University Hospital between April to June 2003 were enrolled. Each patient wore a new N95 mask (3M Model 8210) during HD (4 hours). Vital signs, clinical symptoms and arterial blood gas measured before and at the end of HD were compared.

Results: Thirty nine patients (23 men; mean age, 57.2 years) were recruited for participation in the study. Seventy percent of the patients showed a reduction in partial pressure of oxygen (PaO2), and 19% developed various degrees of hypoxemia. Wearing an N95 mask significantly reduced the PaO2 level (101.7 +/- 12.6 to 92.7 +/- 15.8 mm Hg, p = 0.006), increased the respiratory rate (16.8 +/- 2.8 to 18.8 +/- 2.7/min, p < 0.001), and increased the occurrence of chest discomfort (3 to 11 patients, p = 0.014) and respiratory distress (1 to 17 patients, p < 0.001). Baseline PaO2 level was the only significant predictor of the magnitude of PaO2 reduction (p < 0.001).

Conclusion: Wearing an N95 mask for 4 hours during HD significantly reduced PaO2 and increased respiratory adverse effects in ESRD patients.

11.

. 2016 Jun;24(6):496-508. doi: 10.1016/j.jagp.2016.01.134. Epub 2016 Apr 29.Obstructive Sleep Apnea is Linked to Depression and Cognitive Impairment: Evidence and Potential Mechanisms

Nancy A Kerner 1, Steven P Roose 2

Affiliations

PMID: 27139243

PMCID: PMC5381386

DOI: 10.1016/j.jagp.2016.01.134

Free PMC article

Abstract

Obstructive sleep apnea (OSA) is highly prevalent but very frequently undiagnosed. OSA is an independent risk factor for depression and cognitive impairment/dementia. Herein the authors review studies in the literature pertinent to the effects of OSA on the cerebral microvascular and neurovascular systems and present a model to describe the key pathophysiologic mechanisms that may underlie the associations, including hypoperfusion, endothelial dysfunction, and neuroinflammation. Intermittent hypoxia plays a critical role in initiating and amplifying these pathologic processes. Hypoperfusion and impaired cerebral vasomotor reactivity lead to the development or progression of cerebral small vessel disease (C-SVD). Hypoxemia exacerbates these processes, resulting in white matter lesions, white matter integrity abnormalities, and gray matter loss. Blood-brain barrier (BBB) hyperpermeability and neuroinflammation lead to altered synaptic plasticity, neuronal damage, and worsening C-SVD. Thus, OSA may initiate or amplify the pathologic processes of C-SVD and BBB dysfunction, resulting in the development or exacerbation of depressive symptoms and cognitive deficits. Given the evidence that adequate treatment of OSA with continuous positive airway pressure improves depression and neurocognitive functions, it is important to identify OSA when assessing patients with depression or cognitive impairment. Whether treatment of OSA changes the deteriorating trajectory of elderly patients with already-diagnosed vascular depression and cognitive impairment/dementia remains to be determined in randomized controlled trials.

Keywords: Obstructive sleep apnea; cerebral small vessel disease; cognitive impairment; depression; intermittent hypoxemia.

12.

. 2016 Aug 4;54(1):297-306.

doi: 10.3233/JAD-160329.

Multi-Vitamin B Supplementation Reverses Hypoxia-Induced Tau Hyperphosphorylation and Improves Memory Function in Adult Mice

Lixia Yu, Yuan Chen, Weiguang Wang, Zhonghai Xiao, Yan Hong

PMID: 27497480

DOI: 10.3233/JAD-160329

Abstract

Hypobaric hypoxia (HH) leads to reduced oxygen delivery to brain. It could trigger cognitive dysfunction and increase the risk of dementia including Alzheimer’s disease (AD). The present study was undertaken in order to examine whether B vitamins (B6, B12, folate, and choline) could exert protective effects on hypoxia-induced memory deficit and AD related molecular events in mice. Adult male Kunming mice were assigned to five groups: normoxic control, hypoxic model (HH), hypoxia+vitamin B6/B12/folate (HB), hypoxia+choline (HC), hypoxia+vitamin B6/B12/folate+choline (HBC). Mice in the hypoxia, HB, HC, and HBC groups were exposed to hypobaric hypoxia for 8 h/day for 28 days in a decompression chamber mimicking 5500 meters of high altitude. Spatial and passive memories were assessed by radial arm and step-through passive test, respectively. Levels of tau and glycogen synthase kinase (GSK)-3β phosphorylation were detected by western blot. Homocysteine (Hcy) concentrations were determined using enzymatic cycling assay. Mice in the HH group exhibited significant spatial working and passive memory impairment, increased tau phosphorylation at Thr181, Ser262, Ser202/Thr205, and Ser396 in the cortex and hippocampus, and elevated Hcy levels compared with controls. Concomitantly, the levels of Ser9-phosphorylated GSK-3β were significantly decreased in brain after hypoxic treatment. Supplementations of vitamin B6/B12/folate+choline could significantly ameliorate the hypoxia-induced memory deficits, observably decreased Hcy concentrations in serum, and markedly attenuated tau hyperphosphorylation at multiple AD-related sites through upregulating inhibitory Ser9-phosphorylated GSK-3β. Our finding give further insight into combined neuroprotective effects of vitamin B6, B12, folate, and choline on brain against hypoxia.

13.

Hypoxia-inducible factors as neuroprotective agent in Alzheimer’s disease

Ben Sundra Ashok 1, Thekkuttuparambil Ananthanarayanan Ajith 2, Senthilkumar Sivanesan 3

Affiliations

PMID: 28004401

DOI: 10.1111/1440-1681.12717

Abstract

Beta amyloid (Aβ)-42 peptide and phosphorylated tau protein have been demonstrated as the pathological hallmarks of Alzheimer’s disease (AD). A gradual decline of oxygen and glucose supply to the brain during aging or hypoxia was manifested as a contributing factor to hypometabolism. The brain regions susceptible to hypometabolism are the hippocampus, entorhinal cortex and cognition-associated neocortical regions like parietal, temporal and frontal cortex. In AD patients, the brain regions with hypometabolism can trigger overexpression of amyloid precursor protein and decrease the clearance of Aβ. Aβ and hypoxia can evoke inflammation, oxidative stress and finally neuronal cell death. Among the transcription factors involved in the compensatory mechanism, hypoxia-inducible factor-1 alpha (HIF-1α) has a major role in the cellular adaptation by inducing the expression of several proteins, including vascular endothelial growth factor, erythropoietin and inducible nitric oxide synthase. Therefore, maintaining the HIF-1α level by inhibiting the prolyl 4-hydroxylase was effective to attenuate the nerve damage during hypoxia and postpone the incidence of AD. Agents such as iron chelators, and heavy metals like cobalt and nickel were demonstrated to be effective in maintaining the HIF-1α level in the nerve. This review article discusses the possible role of HIF-1α as a neuroprotector in AD and the future perspectives.

15. https://www.researchgate.net/publication/8371248_The_physiological_impact_of_wearing_an_N95_mask_during_hemodialysis_as_a_precaution_against_SARS_in_patients_with_end-stage_renal_disease

16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7255202/pdf/main.pdf

Wearing a N95 mask increases rescuer’s fatigue and decreases chest
compression quality in simulated cardiopulmonary resuscitation
Yu Tian1, 2
, Xiaopeng Tu1,2, Xianlong Zhou1, 2
, Jiangtao Yu1
, Shan Luo1, 2
, Liping Ma1, 2
, Chang
Liu1, 2, Yan Zhao1, 2*
, Xiaoqing Jin1, 2*
1
Emergency Center, Zhongnan Hospital of Wuhan University, 169 Donghu Road, Wuhan, Hubei,
430071, China
2 Hubei Clinical Research Center for Emergency and Resuscitation, Zhongnan Hospital of Wuhan
University, 169 Donghu Road, Wuhan, Hubei, 430071, China
*Correspondence to: Dr. Xiaoqing Jin, Emergency Center, Hubei Clinical Research Center for
Emergency and Resuscitation, Zhongnan Hospital of Wuhan University, 169 Donghu Road,
Wuhan, Hubei, 430071, China. Email: redjin@wuh.edu.cn; Pr. Yan Zhao, Emergency Center,
Hubei Clinical Research Center for Emergency and Resuscitation, Zhongnan Hospital of Wuhan
University, 169 Donghu Road, Wuhan, Hubei, 430071, China. Email:
doctoryanzhao@whu.edu.cn.

17.
https://www.alzheimers.org.uk/blog/should-person-dementia-wear-face-mask-coronavirus

https://www.considerable.com/health/coronavirus/widely-used-surgical-masks-risky/