We have allergies so bad and after repeated nudging from our doctor...we finally invested in an air purifier. At Costco we bought a Therapure purifier with permanent filter. It uses UV light to eliminate bacteria, germs, and even viruses. It has a Hepa permanent filter, and is Energy Star rated. It was $99, but they offered a $50 Energy Star rebate through Ameren Be sure to check out what other home appliances are included.
Not sure if this is a coincidence, but there are no kids coughing in my home this morning!!! Every night and especially every morning, we have been waking up to coughing and hacking...who knows, but I'm happy :)