Masks and respirators for prevention of respiratory infections: a state of the science review

Greenhalgh et al. (2024) published a review into the science of the use of masks and respirators for the prevention of respiratory infections.

This narrative review and meta-analysis provides a comprehensive analysis of the evidence surrounding the use of masks for preventing the transmission of respiratory diseases, particularly SARS-CoV-2. Here are the key findings:

1. There is strong evidence for airborne transmission of SARS-CoV-2 and other respiratory pathogens.
2. Masks, when worn correctly and consistently, are effective in reducing transmission of respiratory diseases, with a dose-response effect (i.e., better filtration provides better protection).
3. Respirators (e.g., N95 masks) are significantly more effective than medical or cloth masks.
4. Mask mandates are generally effective in reducing community transmission of respiratory pathogens.
5. Non-adherence to masking is sometimes linked to political and ideological beliefs and misinformation.
6. While masks are generally not harmful to the general population, they may be relatively contraindicated in individuals with certain medical conditions, and can disadvantage certain groups (e.g., deaf people).
7. There are environmental risks from the disposal of single-use masks and respirators.

The review proposes future research to better characterize situations where masking should be recommended or mandated, improve mask comfort and acceptability, provide communication support for those disadvantaged by masking, and develop novel materials and designs to improve filtration, breathability, and environmental impact.

The full review can be read here.