That's a problem with your AC unit's poor antibacterial filtration and your home's filters. Filters should be replaced every few months, if not monthly. There's

That's a problem with your AC unit's poor antibacterial filtration and your home's filters. Filters should be replaced every few months, if not monthly. There's also UV lamps that can be installed in AC's, or units that come with them, to sterilize the coil and air.