There used to exist low pressure sodium vapor lamps that emit only the Natrium d-line, which is a ultra warm white monochromatic “color” around 1800K. It is also very economical, can produce 15000 lumen from just a 90W bulb. Before LED that was the most economical electrical light bulb. The only reason they prohibited them was the quicksilver inside the bulbs. What a mistake! Best bulbs ever for outdoor street lights. I hope they can have a comeback.
There used to exist low pressure sodium vapor lamps that emit only the Natrium d-line, which is a ultra warm white monochromatic “color” around 1800K. It is also very economical, can produce 15000 lumen from just a 90W bulb. Before LED that was the most economical electrical light bulb. The only reason they prohibited them was the quicksilver inside the bulbs. What a mistake! Best bulbs ever for outdoor street lights. I hope they can have a comeback.