Gave this Shark Never Change Max air purifier model HP302  a true 30 day test and I can say highly recommend it. The dust shows after 4 weeks running on auto. Then we set up the humidifier. Because we have a water softener that uses salt and peroxide it only took 15 minutes till our air quality dropped to red the unhealthy level. Turned it off and it took 1 hour back to get it back to blue 96 % and it holds their until we put wood in the basement stove and it drop to the low 80’s for about 30 minutes before going back up to 96 to 98 percent good air quality. And we haven’t had any sinus issues after we bought a counter top water distiller From  home improvement store using with the air purifier combination. No while dust going into our lungs. And we only use distilled water we made from the distiller in the cool mist humidifier we use.