As long as you get a hepa filter air purifier, you don't need to clean it every couple of hours. I have one that has an alarm on it that goes off when I need to replace the hepa filter. Usually the hepa filter lasts about 1-2 years. If your air purifier also has a carbon filter, then that needs to be washed every couple of weeks. I've had my purifier for a good 4 months now, and its still doing its job. Make sure you invest in a good quality one though.