BGR has an article on the “scariest” mode of SARS-CoV2 transmission, aerosols, indicating CDC hasn’t been telling us.
Actually, The Hill (Peter Sullivan) noted just now that CDC has finally updated its website with a “sometimes” CDC has somewhat downgraded the concerns over fomites, indicating that transmission through surfaces is possible but probably not common in high doses.
The BGR article refers to an MIT document on Google Docs. The document explains that aerosol transmission is possible without extreme infectiousness (in comparison to measles). Pay close attention to pages 32 and 33, which give some practical advice over the relative risks of some activities. There is a simulation assuming 1% penetration in an area, and 30% effectiveness of masks (they should do better than that) on p. 32. Riding public transportation is safer than I had thought.