Thanks to 10 years of Research and 5 International patents, the Nana captor technology filter is the only one to permanently Destroy formaldehyde, the most harmful indoor pollutant and a human carcinogen according to the world health organization. Formaldehyde, an irritant gas that causes a sensitization but also an aggravation of the symptoms of allergic asthma, is present in 100percent of houses and can be found in cleaning products, building and isolation materials, pressed wood materials or still scented candles. The Nana captor yellow granules inside the filter turns red if saturated, meaning it is the time to Replace the filter. As more formaldehyde is destroyed, the granule turns brown.