The top U.S. public health agency stirred confusion by posting — and then taking down — an apparent change in its position on how easily the coronavirus can spread from person to person on small droplets in the air. The CDC has said that the virus spreads primarily through small airborne droplets, like those that fly through the air when someone coughs or sneezes. Most CDC guidance about social distancing is built around that idea, saying that 6 feet is a safe buffer between people who are not wearing masks. In interviews, CDC officials have also acknowledged growing evidence that the virus can sometimes spread on even smaller, aerosolized particles or droplets that spread over a wider area. That’s one reason public health experts urge people to wear masks, which can stop or reduce contact with both larger droplets and aerosolized particles.