SCIENCE: Mask Wars: While facemasks can’t hurt in the fight against Covid-19, the outrage directed at skeptics is excessive. “Understanding of the mask issue has been considerably clouded by unreliable and badly presented evidence—especially a paper by Renyi Zhang for the Proceedings of the National Academy of Sciences, contributed to PNAS by Mario Molina, who won the Nobel Prize in chemistry for the discovery of the effect of chlorofluorocarbons on the ozone layer. Molina and Zhang are atmospheric scientists with no background in epidemiology, virology, or the propagation of infectious diseases. Within the wider epidemiological community, their paper, which makes wild assertions about the effectiveness of masks while almost completely discounting the effect of other non-pharmacological interventions—and does so based on an unfounded comparison of Wuhan, Italy, and the United States—has drawn largely critical responses, with several noted epidemiologists calling for PNAS to withdraw it. The paper fails not only in its scientific methodology but also in its fundamental grasp of facts and evidence.”