Don't underestimate the efficiency of old-fashioned sodium lamps, they're pretty close to that of LEDs from what I understand. I think part of the reason places are so keen to install LED streetlights is that on paper they have a much longer lifespan than the bulbs in the sodium lamps they're replacing. Also, they're more modern and everyone knows how efficient they are.
interesting, perhaps the new design for the lamp covers is part of it but in my direct experience from a boat there is massively less light pollution with the LEDs which shine downwards only and show in a town on the side of the hill as a set of twinkling fairy lights and in a city over the hill as not much at all whereas the sodium lights produce an orange glow which can be seen for 20 miles or more at night. However, that doesn't say anything about the frequency which could of course be more damaging locally even if it scatters less.
