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. 2024 Aug 22;10(16):e36626.
doi: 10.1016/j.heliyon.2024.e36626. eCollection 2024 Aug 30.

The influence of N95 and surgical masks on carbon dioxide levels: A comprehensive systematic review and meta-analysis

Mahdi Nassri  1 , Parviz Barari  1 , Mohammad Khanizadeh  1 , Sasan Faridi  2   3 , Mansour Shamsipour  2 , Kazem Naddafi  1   2 , Sadegh Niazi  4 , Mohammad Sadegh Hassanvand  1   2
Affiliations

The influence of N95 and surgical masks on carbon dioxide levels: A comprehensive systematic review and meta-analysis

Mahdi Nassri et al. Heliyon. .

Abstract

Objectives: This study aimed to assess the impact of wearing N95 and surgical masks on carbon dioxide (CO2) concentrations during various activity levels, to understand the implications for mask use in different settings, especially in light of the COVID-19 pandemic.

Study design: Systematic Review and Meta-Analysis.

Methods: A systematic review was conducted, retrieving 6798 articles from PubMed, Web of Science, and Scopus databases. Twenty-nine articles met the inclusion criteria. Mask types were categorized into N95 and surgical masks, while activities were classified as low, medium, and high.

Results: The meta-analysis revealed CO2 concentrations (mmHg) for different scenarios: No mask (37.91, 95 % CI: 36.46, 39.35), N95-low (36.83, 95 % CI: 33.57, 40.10), N95-moderate (37.85, 95 % CI: 36.51, 39.20), N95-high (39.51, 95 % CI: 38.00, 41.02), N95 with exhalation valve (35.82, 95 % CI: 32.89, 38.75), N95 without exhalation valve (38.45, 95 % CI: 37.10, 39.81), surgical mask-low (38.31, 95 % CI: 34.48, 42.14), surgical mask-moderate (35.05, 95 % CI: 31.12, 38.97), surgical mask-high (36.07, 95 % CI: 34.18, 37.96).

Conclusions: Our findings indicate that N95 masks lead to higher CO2 accumulation during various activities compared to surgical masks. Moreover, surgical masks exhibit higher CO2 concentrations during low activity compared to moderate and high activities. Notably, CO2 concentrations are higher in N95 masks without an exhalation valve compared to those with a valve. No significant difference was observed between not wearing a mask and wearing either N95 or surgical masks in terms of CO2 accumulation. These results provide important insights for mask selection and usage recommendations in different scenarios.

Keywords: Carbon dioxide; Face mask; Meta-analysis; Pandemic; SARS-CoV-2; Systematic review.

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Conflict of interest statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Mohammad sadegh hassanvand reports statistical analysis was provided by Tehran University of Medical Sciences. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Image 1
Graphical abstract
Fig. 1
Fig. 1
PRISMA flow diagram describing literature research and selection process.
Fig. 2
Fig. 2
The number of publications conducted in different countries.
Fig. 3
Fig. 3
The number of studies conducted in different years.
Fig. 4
Fig. 4
The number of carbon dioxide measurement studies conducted at various zone.
Fig. 5
Fig. 5
Meta-analysis of the effects of no-mask on CO2 concentration. The mean difference estimates (95%CIs) are shown for no-mask.
Fig. 6
Fig. 6
Meta-analysis of the effects of wearing mask plus activity on CO2 concentration. The mean difference estimates (95%CIs) are shown for N95 in low (A), moderate (B), and high (C) activity.
Fig. 6
Fig. 6
Meta-analysis of the effects of wearing mask plus activity on CO2 concentration. The mean difference estimates (95%CIs) are shown for N95 in low (A), moderate (B), and high (C) activity.
Fig. 7
Fig. 7
Meta-analysis of the effects of wearing mask plus activity on CO2 concentration. The mean difference estimates (95%CIs) are shown for SM in low (A), moderate (B), and high (C) activity.
See this image and copyright information in PMC

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