After Zhao Yao arrived at Swamp Prefecture, he sent people to clean the streets of the Swamp Prefecture every day and sprinkle lime in every dark place where bacteria could easily grow. In Zhao Yao's dream, he came to know that the world called these invisible, disease-causing things bacteria. He also had people regularly burn mugwort to dispel some disease miasma.
Not only that, Zhao Yao also sent people to remind the citizens to ventilate their houses and sun their bedding frequently. They should also often sprinkle lime and burn mugwort at home. They should not drink cold water but drink boiled water. Additionally, they should wash their hands before meals, and wash them very clean. After using the toilet, they should also wash their hands.
