Plants absorb CO2 through the process of photosynthesis. A significant amount of plants in the house can help reduce CO2 counts in the air. However, CO2 is usually a lesser concern for air quality in indoor spaces. Airborne chemicals (VOCs), mold, viruses, and other allergens are the common pollutants and causes of health concerns. Plants unfortunately do not work on those types of particulate matter.
On the positive side, plants enrich our indoor air with oxygen.