Filters are an essential element in ventilation systems in ensuring good Indoor Air Quality (IAQ) and levels of hygiene. With the introduction of the new ISO 16890 (2016-12) the filter testing and qualification procedure has been changed to a more realistic classification based on ePM 1, ePM2.5, and ePM10 values. This allows a detailed filter selection based on outdoor particulate matter. Therefore, the new standard is an important improvement. EVIA has produced some further guidance for supplementary explanation.