Lights pulsing dim then bright

I was in someones house and the lights were pulsing dim and bright, it was a very consistent pattern

The person present didnt seem to notice or care, but it was very obvious to me,


What would cause such a thing? they live near a few businesses, but I don't think they're the kind of places that might be using significant loads.
I thought businesses that might use a lot of inductive loads, which I thought might cause such a thing, had to have measures to limit that so it doesn't have a negative affect on the supply grid.


Is there anything else that might cause this?
I don't think anything in the house wiring/installation could cause this.

Could it affect electrical items? ie might it shorten their lifespan or be a hazard,
My understanding was that variation in voltage, would cause changes in current, which could have negative affects. I think this might be caused by possibly caused by frequency changes, potentially caused by loads locally?


Is there any hardware that could smooth out such a thing? short of having some kind of UPS, would a small scale piece of equipment that is used for power factor correction be applicable? could it be determined if it's required and at what cost.