After Molekule begins cleaning, it first does an initial clean up of your room based on the preferences you select. This provides an initial air change, filling your room with purified air. Molekule will then switch to maintenance and retain the cleanliness level of your indoor air.
You can change the mode from the home screen and select the Maintenance cycle to run on any of the modes - Silent, Auto or Boost. You can learn more about the modes here.