Indoor plants compete with humans for oxygen. Some of the flowers have a strong scent that is hard to bear. They can even be carcinogenic. People generally think that flowers can help to absorb CO₂ and provide oxygen. But placing too many flowers in the living room can be harmful.

Photosynthesis only takes place when there is sufficient sunlight. Without sunlight, the plants absorb oxygen and produce CO₂. Too many flowers can release a large amount of CO₂ at night. This can be harmful to health. One family in Changchun suffered from the CO₂ poison while sleeping, and the culprit was the flower.

Research shows that the scent released by flowers can induce cancer in the nose, throat and esophagus. The fluid from the stems and leaves can be poisonous too. We should be careful while decorating our homes with flowers.