Dr. Martin Fischer, Ph.D., from Duke University, developed a simple, low-cost technique to visualize the effectiveness of different face coverings on droplet emissions during normal wear.
Testing several face coverings, the researchers found that the particles can be blocked by some, but not all recommended face coverings. N95s without valves, and surgical, and polypropylene masks worked best. Cotton face coverings provided some coverage. Bandanas and neck fleece didn’t block the droplets very much.