Since the first trial was completed, an important improvement of the air cleaners has arisen. A new panel makes it possible to pre-set the air cleaners at different speeds or on and off at different times of the day, at different days of the week. Once a day, the speed can be changed to another speed or turned off, and once a day, it can be turned back to the original speed in advance. In addition, the pre-set function can be overridden manually at any time. In the first trial, the timer on and off function could turn the air cleaners off once a day and on once a day, with no active cleaning during the timer off intervals, and no weekday differentiation of the timer. This improvement increases the likelihood that the air cleaners will be used at higher (and more noisy) speeds at times when nobody is at home, resulting in lower levels of flying allergen dust levels even at times when people are at home.