A significant number of health care professionals subjected to high-risk situations have been infected by Covid-19 due to the lack of adequate protection equipment or the deficient safety margins that these present. The aim of this study was to investigate whether the use of a personal peripheral sealing device (PSD) on surgical face masks (SM) allows them to achieve double mask properties, by providing two-way protection to professionals or users. The proposed device is a thermoplastic resin ring composed of a reusable and biodegradable polylactic acid (PLA) designed to be used in a healthcare setting. Since it is a thermoplastic device, it can be molded and adapted to each individual, becoming personalized and ensuring a correct adjustment to the user's face. First, a qualitative fit test was performed using a saccharin solution (SS) to evaluate respiratory protective equipment in recruited professionals exposed to high-risk situations of infection by Covid-19. Individuals were divided into an intervention group, who used SM with the PSD, and a control group, who used SM without the PSD. In addition, a quantitative inward air leakage fit test was performed using a 2% sodium chloride (NaCl) aerosol in a sealed cabinet with probes sensitive to this substance, in order to validate the SM with the PSD as a Face Filtering Mask (FFP). Only 5% of the individuals who performed the qualitative fit test with the PSD perceived the sweet taste of the SS, while 100% of the individuals who performed the test without the PSD sensed it (p = 0.0001). In the quantitative fit test, the percentage of air leakage of 2% NaCl aerosol into the SM with the PSD was 6.5%, achieving the same range of air leakage as a FFP mask. Thus, the use of a personalized PLA thermoplastic PSD, together with an inexpensive and widely available SM, could have a significant impact in terms of preventive safety by providing bi-directional protection to its user.