Pulmonary surfactants are a special group of phospholipids and proteins that coat the exterior of your respiratory organs. Why this helps comes down to understanding pulmonary surfactants not as a single layer of fluids, but as multiple layers. “Directly at the boundary with the air, there is a slightly stiffer surface layer. Underneath, there are several layers that should be softer than the surface layer,” study co-author Maria Novaes-Silva described. One path forward may even be concocting artificial surfactants, by identifying the components that make up each individual fluid layer.