This smart air purifier with pollution level sensor continuously checks particles in the air and adjusts its air flow speed accordingly * 4-stage filtration : pre-filter + carbon filter + true hepa filter + ionizer effectively eliminates pollutants * Long-lasting 3-year hepa filter fights dust, smoke, pollen, mold and pet dander * Air quality indicator provides visible color change, indicating the air quality level detected by particle sensor technology * Aham certified and energy star