They definitely seem to help. I have dogs who track in dirt, and then shed hair and dander along with one cat who does the same. So between the dust, dog hair, cat hair and dander from all, it is a constant fight here. I am allergic to a lot of pollens and dust mites. These air filters seem to help along with my air purifiers, and I can say that they definitely do change color when needing to be changed. However, in my house, they only last a month so they are pricey, but I believe I can te...