About the Authors

Loïc Anderegg

Roles Investigation

anderegg@g.harvard.edu

Affiliations Department of Physics, Harvard University, Cambridge, MA, United States of America, Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, United States of America

Cole Meisenhelder

Roles Investigation

Affiliation Department of Physics, Harvard University, Cambridge, MA, United States of America

Chiu Oan Ngooi

Roles Investigation

Affiliation Environmental Health and Safety, Harvard University, Cambridge, MA, United States of America

Lei Liao

Roles Investigation

Affiliation 4C Air, Inc., Sunnyvale, CA, United States of America

Wang Xiao

Roles Investigation

Affiliation 4C Air, Inc., Sunnyvale, CA, United States of America

Steven Chu

Roles Supervision

Affiliations Department of Physics, Stanford University, Stanford, CA, United States of America, Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, United States of America

Yi Cui

Roles Supervision

Affiliations Department of Materials Science and Engineering, Stanford University, Stanford CA, United States of America, SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, CA, United States of America

John M. Doyle

Roles Supervision

Affiliations Department of Physics, Harvard University, Cambridge, MA, United States of America, Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, United States of America

Competing Interests

The authors of this paper have read the journal’s policy and have the following competing interests: S.C. and Y.C. are the co-founders of 4C Air and owns the shares of 4C Air. L.L and W.X. are paid employees of 4C Air. S.C. and Y.C. report non-financial support from 4C Air (https://www.4cair.com/). In addition, S.C. and Y.C. have a patent PCT/US2015/065608 (Air filter for high-efficiency pm2.5 capture) licensed to 4C Air. 4C Air tested face masks from several manufacturers that include 4C Air’s masks and those of other manufacturers. This does not alter our adherence to PLOS ONE policies on sharing data and materials.