The question of whether the coronavirus can be “aerosolized” has stirred controversy for weeks, with a study last month reporting that the virus may be able to stay suspended in air under special circumstances, such as when infected people undergo intubation and other procedures. But the new study suggests that the SARS-CoV-2 coronavirus can be transmitted from one person to another simply by speaking.

Large particles such as those expelled in a sneeze or cough “remain airborne only briefly before settling because of gravity,” Meselson wrote. But “breathing and talking also produce smaller and much more numerous particles” that are “too small to settle.” These aerosols are therefore carried by air currents as mild as those generated by people walking around a room, drafts from open windows and doors, and vents that create air flows.