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Urine is essentially odourless. Bad odour is a chemical reaction between urine, air and water which creates amonnia gas and thats the cause of bad odours. With there being no water in an Eco Ad waterless urinal, there is no chemical reaction and therefore no smell!
The shape of the bowl means that all of the urine is locked in the cartridge via and airtight seal that the urine has to pass through. The cartridge locks the urine inside stoppping any urine, bacteria or smells comeing back through into the wash room. The urinal bowl dries pretty quickly and therefore leaves no detectable smell in the wash room