Erythemal radiation and germicidal radiation are two different things. Germicidal radiation (254nm mostly associated to low pressure lamps) just causes strong skin/eye burns and does not induce suntan. It belongs to shortwave UV-C range. Erythemal radiation belongs mostly to UVB and some short end of UV-A, it causes milder sumburn in large doses and induces suntan and vitamin D synthesis.

Yes, regular glass envelope filters out most of shortwave radiation of a mercury lamp, UVA part generally passes but is not considered harmful, though it induces yellowing in many materials.