Plants absorb CO2 through the process of photosynthesis. A significant number of plants in the house can help reduce CO2 counts in the air. However, CO2 is not usually a concern for air quality in indoor spaces. Indoor air pollution is caused by airborne chemicals (VOCs) and biological contaminants like mold and viruses. Though plants enrich our indoor air with oxygen, they do not remove these pollutants from the air, according to the EPA.