I was worried about the machine scaring one of my cats but she waits for the machine to come on and watches it like a movie. This same cat will not go in a dirty box and since I set the machine on cat activation the box is never dirty. All the products used to maintain my machine are biodegradable and I haven't touched cat litter in 9 months. Lastly, the machine sits almost directly outside my bedroom door and doesn't wake me up at night. Its perfect!