Why can mugwort and calamus kill bacteria?

On the day of the Dragon Boat Festival every year (the fifth day of the fifth lunar month), a bunch of mugwort and calamus are hung at the door, or they are used to burn smokehouses. It is said that they can drive away evil spirits and cure diseases. This folk custom has a long history in our country.

Now it seems that just hanging this bunch of grass at the door or fumigating the house on the Dragon Boat Festival cannot be said to have the power to eliminate disasters and diseases, but it tells us a piece of knowledge: Mugwort and calamus do have the ability to kill bacteria and treat certain diseases.

Mugwort is a plant of the Asteraceae family, and the backs of its leaves are covered with gray-white hairs; Acorus is a plant of the Araceae family, a perennial aquatic herb. The stems and leaves of mugwort and calamus contain some volatile aromatic oils. The main chemical components are phellandrene, β-asarone, etc. After being smoked, they volatilize into the air and have a negative impact on the air. Germs in the air, such as diphtheria, typhoid, Mycobacterium tuberculosis, Staphylococcus aureus, etc., are very lethal. In the fifth month of the lunar calendar, the weather gets warmer and germs begin to multiply actively. At this time, it is also the season when mugwort and calamus are more effective. It makes sense to use them for fumigation and sterilization.