The AHAM AC1-2015 standard sets out how air cleaner manufacturers can define their performance by “the relative reduction of particulate matter suspended in the air in a specified test chamber”. This means their performance is based on cleaning efficiency rates only. We design our purifying fans to go beyond test chamber conditions and focus on real home conditions – this is more than just having an efficient filter. When Dyson engineers set out to design a purifying fan, their research concluded that to clean a whole room properly, you also need to sense pollution events automatically; capture ultrafine pollutants; and project cleaner air around the room using Air Multiplier™ technology. The Dyson purifying fan is designed and tested to do all of this.20