Purafil recommends the Purafil® SPBlend media. These chemical filters remove the widest variety of odors and gases. SP Blend is a combination of Purakol® media, a premium grade activated carbon, and Purafil® SP media, an activated alumina substrate impregnated with the active ingredient sodium permanganate. While Purakol is highly effective at removing VOCs, it performs poorly against hydrogen sulfide, sulfur dioxide, and oxides of nitrogen. By using these media in combination, the Purafil air filter can ensure the removal of all odors.