Heres some filter spectrum data:
http://sweiller.free.fr/spectro/Spec...my-filters.htm
Sodium-Vapour lighting emits around 589.0 and 589.6nm(5890 and 5896 Angstroms)
There are some graphs here:
http://www.samirkharusi.net/spectrograph.html
Note the LPS-P2 cuts well at 5990.
The problem is whether your LP is from low or high pressure sodium. The LPS is great for low pressure(very orange lighting - almost monochromatic), not as good for High pressure sodium(still orange-ish pink but not quite as strong)
Stand under an LPS streetlight and your skin-tone looks kinda grey, if you have orangey-pink skin, its HPS lighting.
Under a HPS light greens and blues(ink on paper etc) are still visible.
The LPS-P2 will still help with the HPS lights tho as the bulk of the emission is in the sodium lines, but there's extra lines in the blue green etc from mercury that will still pass the filter.