Not undetectable by some humans
Product may help my cat - jury is out but this is a warning to humans. I plugged mine in this afternoon. It is in the hallway and my office is a few feet away. After 20 minutes I suddenly tasted a really metallic horrible flavour in my mouth and it really affected my throat. I have left it plugged in but can't get rid of the taste, even though I have been drinking gallons of water. It is not nice.