Question

The mercury used in fluorescent lights is toxic. It would be great if we could find an alternative vapor in the discharge tube that was not toxic. We know that we can make good discharge lamps with sodium – why not use sodium (which produces yellow light) and coat the tube with phosphors to make white light?

Answer 1

First let me talk about the harzards in mercury lamps

Then lets talk about Soduim lamps Hazards

Hence your assumption that one is not reactive than the other is in a way not correct.. Even the phosphors are having toxic effects. But the use is totally dependant on two things one is application and other is cost. So a combination of these two always have an impact on usage of any kind of lamps