Feliway diffuser while on vacation

Do/can you keep the Feliway diffusers plugged in while on vacation?

We noticed our two cats were quite anxious when we came back from our vacation. Because of that I want to buy one or two diffusers to help calm them when we go again next time.

However I am a bit hesitant because of reading some comments about it being a fire hazard. So wondering if people have any advice or recommendations. Thank you in advance!