Turkish Journal of Plastic Surgery

: 2021  |  Volume : 29  |  Issue : 3  |  Page : 166--171

Comparison of effectiveness of four facial masks used during the COVID-19 pandemic using indocyanine green and fluorescent angiography device: A plastic surgeon perspective

Erkan Deniz, Serhat Sibar, Ozgun Kilic, Suhan Ayhan 
 Department of Plastic, Reconstructive and Aesthetic Surgery, Gazi University Hospital, Ankara, Turkey

Correspondence Address:
Dr. Erkan Deniz
Department of Plastic, Reconstructive and Aesthetic Surgery, Gazi University Hospital, 14th Floor, Besevler, Ankara


Background: The pandemic caused by the new type of coronavirus (coronavirus disease 2019) has led to a serious increase in the demand for personal protective equipment, especially the mask. Depending on the increasing demand, many types of masks have been used in the pandemic process between health-care professionals and the community. Aims and Objectives: In our study, it was planned to evaluate N95, green, white surgical, and fabric woven masks with a fluorescent angiography (SPY®) device for protection. Materials and Methods: To evaluate the effectiveness of the masks, models with and without mannequins are used. In both study models, indocyanine green was squeezed from the masks at a distance of 50 cm and the staining values of masks and mannequin faces were evaluated with fluorescent angiography (SPY®) device. Results: The most dyeing fabric was observed in the woven mask, while the least dyeing was observed in the N95 mask. In the model without mannequin, it was observed that the highest protection was in the N95 mask and the least protection was in the fabric woven mask. The most dyeing on the face was observed on the mannequin in which the woven mask was removed, and the least dyeing on the face was observed on the mannequin in which the N95 mask was removed. Green and white surgical masks were found to have similar protective rates. Conclusion: According to the results of this study, where the effectiveness of the mask was evaluated for the first time by using a fluorescent angiography (SPY®) device from a plastic surgery perspective, it was found that the N95 mask had the highest protection, the green and white surgical masks were similar, and the fabric woven mask had the least protection.

How to cite this article:
Deniz E, Sibar S, Kilic O, Ayhan S. Comparison of effectiveness of four facial masks used during the COVID-19 pandemic using indocyanine green and fluorescent angiography device: A plastic surgeon perspective.Turk J Plast Surg 2021;29:166-171

How to cite this URL:
Deniz E, Sibar S, Kilic O, Ayhan S. Comparison of effectiveness of four facial masks used during the COVID-19 pandemic using indocyanine green and fluorescent angiography device: A plastic surgeon perspective. Turk J Plast Surg [serial online] 2021 [cited 2021 Sep 28 ];29:166-171
Available from: http://www.turkjplastsurg.org/text.asp?2021/29/3/166/322670

Full Text


After a new type of coronavirus (severe acute respiratory syndrome [SARS] coronavirus 2) was first reported in Wuhan, China, in December 2019, coronavirus disease 2019 (COVID-19) was declared as a pandemic by the World Health Organization on March 11, 2020.[1] During the pandemic, the American Centers for Disease Control and Prevention recommended a number of measures to protect individuals such as knowing the spread of the virus, ensuring frequent hand hygiene, preventing close contact, use of personal protective equipment, frequent cleaning, and disinfection.[2] In line with these recommendations, as in the previous SARS and influenza pandemics, there has been a boom in the demand for personal protective equipment, especially for medical masks, during the current COVID-19 pandemic. Owing to the difficulties in obtaining medical masks as a result of the increasing demand, the use of fabric weaving, reusable masks has come to the agenda and has been widely adopted by the public.[3],[4],[5],[6] This study aimed to evaluate the effectiveness of the filtered (N95) and medical-surgical masks, which are widely used by the health workers combatting with the pandemic in the front lines, and fabric masks commonly used by the public against aerosol contamination using indocyanine green and fluorescent angiography methods commonly used in plastic surgery.

 Materials and Methods

Study design

Four different types of masks were used for studies to evaluate filtration efficacy. One of the masks was an N95 mask (Dräger®, Lübeck, Germany), which is used by the group of health personnel at high risk of infection (intensive care and infection clinics) in our hospital during the pandemic; the other two are green (Lohmann and Rauscher®, Rengsdorf-Germany, Vienna-Austria) and white (Asimed Medikal®, Manisa, Turkey) surgical masks used by health personnel at low risk of infection; and the last one was a fabric woven polyester (93%) black mask widely used by the public [Figure 1].{Figure 1}

Study design made with mannequin models

Four mannequin head models were used to evaluate and simulate the effectiveness of the masks after wearing them on the face (mannequin 1 = green surgical mask, mannequin 2 = white surgical mask, mannequin 3 = fabric woven mask, and mannequin 4 = N95 mask). A blind researcher devoted 5 min to each mannequin's head to fit a mask of any type in the most appropriate way possible. To simulate live viral contamination, fluorescent dyeing method was used with reference to previous similar studies in the literature.[7] Because the use of multiple masks would create an accumulation of fluorescent paint on the face of mannequins and cause errors in the measurements, assessments were made with a single mask on each model. Fluorescent dye solution was prepared by adding 25 mg indocyanine green (Aurogreen®, Aurolab Pitampura, New Delhi) into 500-cc isotonic sodium chloride solution. The fluorescent dye was then squeezed twice from a spray cap bottle at a distance of 50 cm to the face of mannequins and masks to simulate sneezing or coughing, and the amount of dye on the face of the mannequins after removing the masks was quantitatively measured using the SPY® fluorescent angiography device (Novadaq Technologies, Inc., Ontario, Canada) [Figure 2].{Figure 2}

Measurements on the obtained images were made by five plastic surgeons (by assigning a reference value of 100 to the most painted point) at 10 different points for each mask surface and the face areas of the mannequins under the mask. Numerical staining values were separately calculated by averaging the obtained data [Figure 3]. In addition, the stained areas of the masks and mannequin faces were evaluated using ImageJ® (NIH, LOCI, University of Wisconsin) software.{Figure 3}

Study design without mannequin models

Without using mannequin models, fluorescent dye solution was sprayed twice onto the outer surface of the masks at a distance of 50 cm. Five masks were used for each mask type, with a total of 20 masks. The images obtained from the outer and inner surfaces of the masks were measured for staining values at ten different points by five plastic surgeons. The reduction factor (RF), which is an important parameter in assessing the filtration efficacy of masks, was calculated by dividing the staining on the outer surface by that on the inner surface.

Statistical analysis

Differences between staining values obtained in different experiments were statistically assessed. Statistical evaluation was performed using IBM SPSS 11.5 (SPSS Inc., Chicago, IL, USA) package program. In addition to descriptive statistics, one-way analysis of variance was performed for multiple group comparisons in terms of staining values. Post hoc assessments were conducted using Games–Howell test. P < 0.05 was considered statistically significant.


Results of the study conducted with mannequin models

Fluorescent Staining Results

Descriptive statistical values in terms of fluorescent staining values on all masks and on the face of mannequins after removing the masks are shown in [Table 1].{Table 1}

SPY® measurements on mask surfaces revealed a statistically significant difference in terms of mean staining values according to mask types (P < 0.05). Although post hoc tests revealed no significant difference between green and white surgical masks (P > 0.05), there was a significant difference in all other binary comparisons [Table 2].{Table 2}

Accordingly, the least staining was observed on the N95 mask, whereas the most staining was observed on the fabric woven mask (fabric mask > green surgical = white surgical mask > N95 mask). It was also observed that in all mannequins, the periorbital region was most intensively stained among the areas not covered by the mask [Figure 3].

There was a statistically significant difference in SPY measurements between the models in terms of staining on the face areas under the mask once the masks were removed (P < 0.05). Post hoc analysis revealed that there was no significant difference between mannequins 1 and 2 (P > 0.05), but there was a significant difference in all other binary comparisons [Table 3]. Accordingly, the least staining was found on mannequin 4 (N95) and the most staining was found in mannequin 3 (fabric woven) (mannequin 3> mannequin 1 = mannequin 2> mannequin 4).{Table 3}

ImageJ data results

Using ImageJ® program, the stained areas of the mask on each mannequin and the painted areas on the face after removing the masks were calculated in terms of percentages [Figure 4]. Accordingly, the most stained mask surface and mannequin face area were observed in case of the fabric woven mask, whereas the least stained mask surface and mannequin face were observed in case of the N95 mask. Although the stained areas of green and white surgical masks were equal in terms of percentages, when the masks were removed, the face of the mannequin wearing a green surgical mask was more stained than that of the mannequin wearing the white surgical mask [Table 4]. Because only one of each mask type could be evaluated, the results obtained were not statistically evaluated.{Figure 4}{Table 4}

Experimental results without mannequin models (reduction factor)

Descriptive statistics in terms of staining values observed in mean RF calculation of masks are shown in [Table 5]. Although coefficients vary from mask to mask in the literature, the values range from 1.1 to 55. A statistically significant difference was found between the masks in terms of mean RF values (P < 0.05). Based on post hoc analysis, there was no significant difference between green (RF = 1.47) and white surgical masks (RF = 1.55) (P > 0.05), but a statistically significant difference was found in all other binary comparisons (P < 0.05). The highest RF was detected in the N95 mask (RF = 36.8), whereas the lowest RF was detected in the fabric woven mask (RF = 1.02) (RF N95 mask > RF green surgical mask = RF white surgical mask > RF fabric woven mask).{Table 5}


Although the conception of the idea of using masks dates back to 1897, the COVID-19 pandemic that we face today has rekindled the debate about the importance and functionality of masks. Although studies conducted on SARS and influenza pandemics have reported some types of masks (N95) to be highly effective in preventing aerosol contamination, there are a limited number of studies assessing the protective efficacy of surgical masks against aerosol contamination.[8],[9],[10],[11] Taking this into consideration, the aim of the present study was to evaluate the protective efficacy of the most commonly used masks during the COVID-19 pandemic among high-risk (N95) and low-risk (surgical mask) groups of health workers and the general public (fabric woven mask) from a plastic surgery perspective. The study model was planned according to previous in vitro models, and protective efficacy was assessed on mannequin head models. Breathing creates moistening on the inside of the mask and can increase permeability due to liquid diffusion (capillary) effect; however, the effect of this variable on mask permeability could not be evaluated in this study owing to the lack of a respirator. Potassium chloride solution, corn oil, and live viral particles have been used in previous mask studies to evaluate filtration efficacy; however, indocyanine green was preferred in the present study.[7],[12],[13],[14] This is the first study in the literature using SPY® for quantitative evaluation. When all data obtained from experiments conducted with or without mannequin models were evaluated, the N95 mask worn by high-risk health-care workers was found to be the most effective mask as the mask and the mannequin head showed the least amount of staining in SPY® imaging, the RF of the N95 mask was higher than that of the other three mask types, and these differences were statistically significant. Fabric woven masks commonly used by the public during the pandemic were found to have the lowest protective efficacy. In all models, the periorbital area not covered by the mask was intensively contaminated with dye, indicating that the use of masks alone will not be sufficient to be protected against aerosol contamination, thereby showing the necessity of implementing additional measures (such as the use of glasses and face shields).

ImageJ data revealed that the lowest staining area was obtained in case of the N95 mask. This was attributed to the highly hydrophobic surface structure of the N95 mask. In contrast, the most extensive staining was observed in case of the fabric woven mask. This was attributed to the flexible and porous structure of the mask, resulting in fluid entrapment. In addition to the filtration capacity, the effectiveness of a mask is determined by how well it fits on the face (face seal).[15],[16],[17] In fact, more staining observed in ImageJ data with the green surgical mask than with the white surgical mask was attributed to the elastic strap of the white surgical mask, resulting in a better face seal. It was seen that the N95 mask better fits on the face of the mannequin than the surgical masks, and this was also considered to be an effective factor in protection. On evaluating comparative mask studies in the literature, some publications have reported that the N95 masks show higher or similar protective efficacy compared with surgical masks.[11],[14],[18],[19] Consistent with our findings, it has been reported that fabric or cloth woven masks generally have the lowest protective efficacy and should be preferred if there is difficulty in obtaining masks during a pandemic.[6],[16],[20],[21] The use of SPY® for the first time in the literature to evaluate mask efficac1y and eliminating the need for using live virus were the strengths of the present study. The limited number of mannequin models and the lack of respiratory function in mannequins were the limitations of the study. In the literature, it is noted that the standardization of comparative mask experiments is quite difficult. We aimed to provide the readers with a plastic surgery perspective when evaluating the efficacy of masks.[13],[22],[23],[24],[25],[26] Several factors such as allocation of 5 min for optimal fitting of masks to each mannequin head, multiple point measurements with SPY® device performed by five plastic surgeons, and the large number of masks used without mannequin heads to reduce the margin of error were employed to reduce statistical error and achieve a certain standardization.


In this study, we evaluated the protective efficacy of masks from a plastic surgery perspective with the SPY® device that we frequently use in flap perfusion analysis. Based on the results of this study, the N95 masks have the highest protective efficacy, followed by the green and white surgical masks with similar efficacy, whereas the fabric woven masks commonly used by the public have the lowest protective efficacy.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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