Active carbon is usually made of organic materials e.g. wood, peat, nutshells or lignite and hard coal.
Active carbon is used in the automotive industry, in extractor hoods, ventilation and air conditioning systems, as well as in chemical, medical and drinking water treatment processes. The pores are similar to a sponge and have an inner surface; on this surface four grams of active carbon approximates the size of a football field. These extremely large adsorption surfaces ensure excellent filtering and a large storage capacity for many undesirable dyes, flavours and odours made of gases, vapours and fluids.
It is, however, very difficult to predict the filter life because the use of the carbon depends on the problem substances that need to be removed.
One option would be to document weight gain. If the weight of the carbon no longer increases, it is exhausted. As soon as odours occur, this is an indication that the filter needs to be changed. However, this is only to be recommended for harmless odours.