If you don’t clean and maintain the filter properly, a layer of dust and grime will start building up on the filter. This can damage the filter completely and quickly. It also promotes the growth of mold over the filter. It spreads bacteria and you might soon start noticing a lot of dust and pet dander in the air. Thus, you should always maintain the air purifier properly. You must always turn off the purifier while cleaning it. Clean it regularly to keep your house free from dirt and other microbes.