Source:
https://scmp.com/article/507912/white-lights-big-cityWhite lights, big city
White led
Colour LEDs are easy to manufacture, but white LEDs are tougher to make. White light is produced by adding phosphor to a blue LED.
HOME LIGHTING
Backers of the technology envision white LEDs replacing tungsten lighting in the home. Because of high manufacturing costs, this could take several years.
TRANSPORT
The initial market for LED lighting has been in the transport sector. LEDs last as long as 100,000 hours, compared with 5,000 for normal lighting, thus reducing maintenance costs.
OUTDOOR SIGNAGE
Another market for LEDs is outdoor signage, such as this Philips display. LED lighting uses less energy, cutting electricity costs for advertisers.