It's also a surface-borne virus, and so a mask alone is perhaps not that effective. This is why nurses and doctors wear not just masks, but gloves, eye protection, and gowns when treating active COVID patients.

However, wearing such biohazard-level protection isn't really plausible for daily use, and outdoors, transmission is negligible, so it probably makes little sense for people out for a walk to mask up. Maintaining good hand hygiene practices (i.e. wash hands immediately upon entering the home, and certainly before food preparation, don't touch your face with your hands, etc.) is probably more effective.