Florescent lights can cause interference also. not normally a big problem unless you are an amateur radio operator . (I am)
Many devices produce radio frequencies as a byproduct of its operation. Computers do also. Almost everything That you plug in produces some radio frequency energy. In many cases it is the power supply for the device. "Switching " power supplies are used as the power source in most of these devices. (cheap, light weight and efficient)
The amount of interference varies widely even for the same device. Don
