OK, I'll be more forceful. I'm sure the problem is with IR and I'll provide a link next time if I have to look it up. No further comment on UV.
In fact, I believe that the sodium flare is more of a nuisance and an impediment to seeing detail on your work rather than being harmful. There are hothead workers who do detail work that does not produce the sodium flare, and often you see them working without dydimium for that reason, when they still should be using IR filter glasses.
When didymium glasses were first used, all they did was cut sodium flare. If you read evaluations by glass eyewear makers, they say that the old style didymium without IR protection are not recommended. However, "didymium" has become a generic term for lampworking glasses that filter the sodium flare and modern glasses do filter IR.
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