## 4 Conclusions  
This study evaluated the filtering and transmissibility properties of face mask layers individually and in combination using experimental data and mathematical analyses that provided velocity profiles and filtration efficiency. Air flow velocity measurement before and after passage through the edge-sealed masks has established their filtration efficiencies. These have been assessed experimentally using an air duct mask container fitted with pitot tubes at entry and exit within the centre and edges of the rectangular air duct. The particle size and distribution within the fabric weave were assessed by SEM. The porosity and fiber diameter of six different face masks have been investigated. Of these, _Reusable Cotton_ has the largest, and _FFP3_ has the lowest pore size. _Antiviral_ and _Silk_ masks show comparable pore sizes equal to approximately twice the pore size of the surgical and FFP2 masks. Fiber diameters lie in a narrow range; the greatest and lowest sizes apply to _Surgical_ and _Silk_ fibers, respectively. Twelve healthy volunteers recorded the temperature and  
Figure 8: Time-dependent temperature distribution for all the six face masks during a breathing cycle at two-time points, inhalation peak (at 3 s) and exhalation peak (at 1 s). Results are displayed for FFP3 during the (**a**) inhalation and (**b**) exhalation peaks, FFP2 during the (**c**) inhalation and (**d**) exhalation peaks, surgical during the (**e**) inhalation and (**f**) exhalation peaks, reusable cotton during the (**g**) inhalation and (**h**) exhalation peaks, silk during the (**i**) inhalation and (**j**) exhalation peaks, antiviral during the (**k**) inhalation and (**l**) exhalation peaks.  
humidity for both the mask and their body temperature. The results indicated an increase in temperature and humidity while wearing the masks, with no clinically significant change in body temperature. The _FFP2_ and _FFP3_ masks showed the greatest filtration efficiencies, each being in excess of 95%, a feature of the multi-layered designs. The simulations showed that _FFP2_ and _FFP3_ masks gave higher filtering efficiencies for small particles (<5 \(\upmu\)m). The velocity distribution simulations showed that all six face masks have a low air velocity (-0.8-1.4 m/s) inside the mask (within the nose and mouth). Moreover, the temperature distribution simulations revealed small variations during breathing transmission. This study has provided information on an effective medical face mask design for the control and prevention of the spread of infectious diseases in the most common settings.  
Conceptualization, M.R. and D.R.; data curation, M.R. and D.R.; formal analysis, M.R. and D.R.; methodology, M.R., D.R., and F.P.; software, F.P.; supervision, M.R. and D.R.; validation, M.R., D.R., and S.H.; writing--original draft, M.R., D.R., and F.P.; writing--review & editing, M.R., D.R., and S.H. All authors have read and agreed to the published version of the manuscript.  
No funding was received for conducting this study.  
This study, conducted in accordance with established ethical guidelines and involving twelve healthy human volunteers, received ethical approval from the Brunel University Research Ethics Committee under the reference number 46938-MHR-Feb/2024-49825-3 (8 February 2024).  
Informed Consent Statement: Informed consent was obtained from all participants. Additionally, parental consent was obtained for participants under 18, ensuring compliance with all relevant regulations.  
The data presented in this study are available on request from the corresponding author due to privacy and ethical restrictions.  
We would like to thank [PERSON] and [PERSON] for their technical help during the design process. The Mechanical Department of Brunel University London supplied the test facilities. The volunteers are thanked for their participation in this research activity.  
The authors declare no conflicts of interest. However, reproduction or commercial use of this work is not permitted without prior written consent from the authors.