Do they a really have good evidence for the ratio of air-borne versus surface-borne transmission for COVID-19?
People do emit aerosols when speaking (
https://www.nature.com/articles/s41598-019-38808-z) and the louder they are, the more they emit. Two minutes of speaking and breathing (i.e, conversing) equals about 15 seconds of coughing. Singing is about 6X worse than speaking and is about as bad as coughing (it's not surprising that 75% of that choir practice group caught it from some asymptomatic carrier). I pity the healthcare workers who have to look at someone's throat -- saying "ahh" is as bad as coughing. Even normal breathing emits microscopic particles that can contain viruses. Finally, some people emit 10X the average number of particles for reasons unknown. These microscopic particles emitted by breathing/talking/singing are more infectious than the visible globules from coughing because they are so small that they remain in the air for longer and can be more easily inhaled deep into the lungs.
Bottom line: if you can smell someone's second-hand smoke, cologne, perfume, laundry detergent fragrance, bad breath, or body odor, you are probably inhaling whatever they are exhaling.