An interesting read on many levels.
I wonder how many magnetic ballast fluorescent tubes they use at the local school, and how many of the migraine sufferers that come to see me have luminaries, particularly the new LED’s which flicker!
I will be asking the question.
Handy tip for checking as well 
“If you can persuade the shop to ignite the lamp, then you can tell if it is flickering using a child’s fidget spinner. If the spinner appears to rotate in a direction opposite to the direction of spin – just as the spokes on wagon wheels appear to turn backwards in old westerns – then the lamp is flickering, whether you are aware of the flicker or not.”
Image credit Unsplash (free) 2018 09 12