Article Text

Original research
Triaging of respiratory protective equipment on the assumed risk of SARS-CoV-2 aerosol exposure in patient-facing healthcare workers delivering secondary care: a rapid review
  1. Prashanth Ramaraj1,
  2. Jonathan Super1,
  3. Ruben Doyle2,
  4. Christopher Aylwin1,
  5. Shehan Hettiaratchy1
  1. 1 Major Trauma Centre, Imperial College Healthcare NHS Trust, London, UK
  2. 2 Department of Engineering, Imperial College London, London, UK
  1. Correspondence to Dr Prashanth Ramaraj; prashanth.ramaraj13{at}


Objectives In patient-facing healthcare workers delivering secondary care, what is the evidence behind UK Government personal protective equipment (PPE) guidance on surgical masks versus respirators for SARS-CoV-2 protection?

Design Two independent reviewers performed a rapid review. Appraisal was performed using Critical Appraisal Skills Programme checklists and Grading of Recommendations, Assessment, Development and Evaluations methodology. Results were synthesised by comparison of findings and appraisals.

Data sources MEDLINE, Google Scholar, UK Government COVID-19 website and grey literature.

Eligibility criteria Studies published on any date containing primary data comparing surgical facemasks and respirators specific to SARS-CoV-2, and studies underpinning UK Government PPE guidance, were included.

Results Of 30 identified, only 3 laboratory studies of 14 different respirators and 12 surgical facemasks were found. In all three, respirators were significantly more effective than facemasks when comparing protection factors, reduction factors, filter penetrations, total inspiratory leakages at differing particle sizes, mean inspiratory flows and breathing rates. Tests included live viruses and inert particles on dummies and humans. In the six clinical studies (6502 participants) included the only statistically significant result found continuous use of respirators more effective in clinical respiratory illness compared with targeted use or surgical facemasks. There was no consistent definition of ‘exposure’ to determine the efficacy of respiratory protective equipment (RPE). It is difficult to define ‘safe’.

Conclusions There is a paucity of evidence on the comparison of facemasks and respirators specific to SARS-CoV-2, and poor-quality evidence in other contexts. The use of surrogates results in extrapolation of non-SARS-CoV-2 specific data to guide UK Government PPE guidance. The appropriateness of this is unknown given the uncertainty over the transmission of SARS-CoV-2.

This means that the evidence base for UK Government PPE guidelines is not based on SARS-CoV-2 and requires generalisation from low-quality evidence of other pathogens/particles. There is a paucity of high-quality evidence regarding the efficacy of RPE specific to SARS-CoV-2. UK Government PPE guidelines are underpinned by the assumption of droplet transmission of SARS-CoV-2.

These factors suggest that the triaging of filtering face piece class 3 respirators might increase the risk of COVID-19 faced by some.

  • infection control
  • occupational & industrial medicine
  • public health

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  • Contributors All authors meet ICMJE’s four criteria of authorship. PR conceived the idea, contributed to the methodology, conducted the search, extracted and appraised data and wrote the article. JTS contributed to the methodology, conducted the search, extracted and appraised data and reviewed the article. RD contributed to the writing of the article, and provided review and guidance throughout. CA contributed to the writing of the article and provided review and guidance throughout. SH contributed to the development of concept, contributed to the writing of the article and provided review and guidance throughout. All authors approved the final manuscript and article submission. Guarantorship: the corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding The Wellcome Trust kindly covered the Article Processing Charges of this manuscript. Access to the Wellcome Trust Article Processing Charges block grant was sought and secured after the manuscript was accepted for publication by BMJ Open.

  • Competing interests All authors have completed the ICMJE uniform disclosure form at and declare: no support from any organisation for the submitted work; no research grants and honorariums. RD has recently begun to design not-for-profit, small scale items of PPE for the amelioration of the widely documented PPE stock crisis, aside from RD’s core business; no other relationships or activities that could appear to have influenced the submitted work.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request. The authors will support data sharing on request by emailing the corresponding author, PR.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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