Introduction

The use of face masks (FMs) has become widespread as part of a multi-faceted approach to limit spread of the COVID-19 virus. In the past, use of the mask was limited to occupational health and safety settings, as well as use by individuals to combat impact of air pollution, allergies, and risk of infection in immunosuppressed people The increased use during the pandemic has highlighted problems in their use.

As of December 2021, more than 86% of the world's population lived in countries that recommended or mandated FMS in public; more than 130 countries have mandated the masks [1] The wearing of masks along with physical distancing or during exercise has been contentious [1, 2].

A well-performing FM must have the following four basic ergonomic requirements:

  • (1) Protect the respiratory system from the polluting or infectious agent.

  • (2) Allow adequate ventilation.

  • (3) Fit the face well.

  • (4) Ensure good protection and comfort during normal activities.

The demand for masks has led to new approaches to the design of face masks [3]. Different types of FMs are listed in Table 1 [3, 4].

Table 1 The different types of face masks
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Rationale for the review

Reports on potential side effects of mask wearing led us to query the safety implications of wearing masks [5]. The side effects include a false sense of security, reduced compliance with other measures

and contraindications to mask wearing including young children, persons with breathing difficulties or who are unconscious, incapacitated, etc. [4].

Methods

We performed a systematic review of published studies investigating the safety of FMs categorized to different groups, i.e., children, pregnant women, patients with neurodegenerative diseases, cognitive impairment, obesity, lung/cardiac/renal diseases, psychiatric disorders, eye or upper airway diseases. We searched Medline/PubMed and EMBASE using the search strategy reported in Supplemental files, with no time and language restrictions.

The search and screening process was independently conducted by two researchers (MLR and DDS) with no time restrictions. Reports were considered potentially eligible for this review if they assessed the safety, risks and/or the respiratory impact of FMs. We included papers about the impact of FMs on communication, especially in noisy environments. Figure 1 shows the study selection process. Exclusion criteria were as follows: papers not peer reviewed, not focused on risks, safety or impact on respiratory function, no reported exposure to any type of face mask, not focused on age range or disease. From each paper we extracted the following: authors’ names, year of publication, study design, sample size, safety indicators and/or respiratory parameters, safety and/or respiratory outcomes.

Fig. 1
figure 1

Studies‘ identification and selection

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Given the heterogeneity of studies, results were analyzed thematically. We used PRISMA guidelines to report our findings.

Consensus recommendations

Following the systematic review, we arbitrary selected a panel of specialists with experience and/or interest in patient safety (1 gynecologist, 1 pediatrician, 3 internists, 1 pulmonologist, 1 ear-nose- throat specialist, 1 public health and 2 occupational medicine physician, 1 ergonomist, 1 coroner) to address specific recommendations. A Delphi consensus approach was used [6]. A detailed document with a research evidence summary, including methodological details of included papers, was sent to each panelist who reviewed the document and gave their own recommendations for any thematic area anonymously with the rationale for their proposal. All statements with the associated rationale of the proposal were sent back to the panelists to choose one option in any thematic area. We conducted three rounds to reach an acceptable level of consensus.

Results

Our research retrieved 3718 papers, of which 3577 were excluded after title/abstract screening, 66 after full test reading and 19 because of duplication; seven papers were identified from the reference list. We included 63 eligible papers, published between 1995 and January 2022. Details are provided in Table 2. We divided them into 12 thematic categories according to the investigated population/safety issues.

Table 2 Eligible studies grouped in twelve thematic categories
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Key lessons from all the papers are that each group may experience challenges to wearing masks. In each category there are specific challenges. These include the following:

  • Discomfort (in all groups).

  • Impact on respiratory function in people with respiratory disease, children, elderly, people with heart disease.

  • Irritation of the skin especially for people with skin disease.

  • Communication problems for people with a hearing loss.

  • Issues with mask reuse.

Side effects with respirators [53,54,55,56] include concentration problems, reduced working capacity [56], respiratory difficulties [48, 56,57,58], fogging glasses, difficulty with facial recognition and psychiatric symptoms. Headache was reported after prolonged use.

Discussion

To the best of our knowledge, this is the first systematic review on FMs-related patient safety issues. We have assessed the safety, the risks and/or the respiratory physiological impact of FMs in age ranges or disease categories. We could not pool data as in a meta-analysis, nor could we cover the entire spectrum of diseases as too few papers were retrieved and they were heterogeneous in nature.

In Table 3 we summarize the recommendations based on our review to facilitate safe evidence- based use of FMs in different categories.

Table 3 Recommendations for a safe use of respiratory protective devices during epidemic outbreaks in different categories of patient
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Published evidence suggests that mask-related safety issues included the following:

  • Increased breathing resistance with subsequent increased respiratory effort.

  • Decreased FiO2 and increased FiCO2.

  • Inconvenience in the face, head, and neck areas, increased humidity, temperature, pressure on the nose, around the ear lobes.

  • Psychosocial effects.

In addition, there may be inadequate protection to people who cannot tighten their face properly due to malformations or a following an operation of the skull or face.

Pregnant women have an increased risk for severe illness from COVID-19 and are at a higher risk for preterm birth and stillbirth and other pregnancy complications [72]. Interactions between FMs use and pregnancy-related rhinitis, induced airway changes (increased breathing resistance and residual volume loss) and pregnancy-related dyspnea remain to be solved [70]. Wearing FM during childbirth is not associated with any adverse outcome for mothers or newborns [73].

Most of the studies noted that the pandemic negatively affected people’s mental health. Mask- wearing is associated with mask-related panic attacks, worsening mood, depressive symptoms, anxiety and sense of suffocating [48, 49, 57]. People with mental health can have difficulties to follow the recommendations due to their disorders [45, 46]. For example, children with ASD for example, struggle to tolerate FMs for more than 15 minutes [50, 51].

Most people with Alzheimer Disease had no knowledge of the pandemic and did not wear the masks properly even with help, leading to increased risk of infection [34, 35]. We retrieved only an expert opinion paper about people with epilepsy. FMs may induce hyperventilation which can activate seizure activity [74].

People who have had a laryngectomy have an anatomical and/or surgical alteration of the upper airways that enhances susceptibility to contagion. They require multiple protection [75] in people with allergies and rhinopathology FMs have an advantage of preventing exposure to pollen grains [24, 25], but in 70% with and without chronic rhinitis the FM seemed to decrease the quality of life [76].

The literature regarding FMs and eye disease showed that not only there are mask-related symptoms: MADE (mask-associated dry eye), eye irritation and inflammation can cause increased face touching and spread of COVID-19. Artifacts could also occur in the results of the examination of the visual field [29,30,31,32,33].

The literature on physical exercise and FMs is limited. In general, FFP2/N95 masks are perceived as more uncomfortable than surgical mask [27]. Exercising at low or moderate intensity when wearing FM can prevent an increased risk of obesity, cardiovascular disease, and depression [36, 37].

Common SMs are responsible for a loss of hearing more than 20% while F-PPE (e.g. FFP3 masks combined with a face shield) could cause a reduction of almost 70% and significant verbal communication issues [77] to improve intelligibility without altering physical distance, the clinician had to increase the voice volume increasing the risk of loss of confidentiality [78]. Using written order and/or read-back procedure, speech-to-text mobile apps, written scripts (e.g., chalkboard) or masks with a plastic transparent panel over the mouth, make communication easier for hearing impairment patients [79].

In children N95 respirator wearing is associated with a reduced FiO2 and/or SpO2and/or PaO2 and an increased ETCO2 and/or PaCO2, proportionally to the duration of use and disease severity [7]. Recommendations for children are provided by the CDC and the American Academy of Pediatrics [70, 71].

Safety of FMs have not been yet investigated in patients with heart failure, gastroesophageal reflux, obesity, adenoid hypertrophy, and cognitive impairment.

Extended use, reuse, or decontamination of SMs and N95 respirators may result in inferior protection. Some evidence suggests that reused and makeshift mask should be used when medical- grade protection is unavailable [68]. Reuse of masks has also led to a debate given the cost and the environmental impact of discarded masks. The most frequent methods used are the decontamination with hot water and ethanol or specific cleanser because it is more suitable for people to perform at home. Information campaigns are required to promote the correct use of masks and limit the infection rate [68].

With the greater obligation to use FM, some recommendations should be made on legal medical issues. The emergency has forced governments to act based on two opposing and antithetical presumptions. In particular, the policy of mandatory mask wearing was established by assuming that the population was a potential vector of infection and that the use of FMs was free from side effects. However, not being able to go out or enter a place without a mask can be considered a restriction of individual freedoms. Similarly, a contraction of the fundamental and inalienable right to health could occur when the obligation involves individuals suffering from specific pathological conditions which could be aggravated by wearing a mask.

Nonetheless, according to current evidence, the use of FMs is complementary to other measures such as physical distance and hand hygiene. Therefore, to reconcile personal protection with public health needs, it is recommended that we recommend appropriate and safe use [80] of FMs through targeted educational campaigns and more detailed guidelines rather than solely through mandating, because the reduction of the virus and the benefits of wearing FMs outweigh the discomfort [58].

Limitations

We may have missed minor papers with our search strategy as there are no specific terms to univocally indicate protective FMs. In addition, recommendations change when new evidence is published. Finally, published papers do not provide data on major clinically relevant outcomes, such as adverse effect-related diseases or hospitalization. Evidence on respiratory impact in sick/frail subjects and mask-related patient safety issues is limited and heterogeneous; current expert-opinion recommendations need to be validated with large scale studies.

Conclusions

In general, evidence demonstrates that benefits of wearing face masks exceed discomfort; anyway an “air break” after 1–2 hours consecutively of mask-wearing can be a good practice for people with respiratory function compromised by diseases or in particular conditions (i.e. pregnancy, epilepsy, etc.). The present COVID-19 pandemic, where different public health agencies and governments have recommended universal use of FMs, represents a unique opportunity for collecting large amount of real-world data.