The COVID-19 virus is primarily transmitted by breathing in air which an infected person has exhaled. We need to figure out how to ventilate our buildings so exhaled air is drawn away from other people. Outside is likely a safe place to be, as long as we’re not too close to other people.
Barbers could wear a mask with two hoses, one for breathing in clean air from a safe location, the other for breathing out potentially infected air to another location sufficiently far from the customer. A simple one-way valve in each hose will enforce the airflow direction. Combined with decent ventilation indoors, some sufficiently separated chairs outdoors for waiting customers, and maybe I can get a haircut again.