On Friday, the US CDC updated guidance regarding the use of masks among the general public. Based on data collected over the course of the pandemic, the CDC now “recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies) especially in areas of significant community-based transmission.” The new guidance is based on the current understanding that individuals with no symptoms or mild symptoms can transmit SARS-CoV-2 to others, so wearing a mask could reduce that risk. The mask use aims to trap droplets expelled by the mask wearer in order to reduce the amount of virus potentially released into the environment. The CDC emphasizes that respirators and surgical masks should be reserved for healthcare personnel and that wearing a mask does not replace existing social distancing guidance. The CDC also provides instructions for constructing homemade masks for this purpose—as well as donning, doffing, and washing instructions.