What is Carbon Dioxide and How Do You Reduce It?

Carbon Dioxide (CO2) is all around us.  It is a colorless, odorless gas that is naturally occurring within the atmosphere.

Indoor air quality has a huge impact on our health and productivity.  In fact, increased levels of carbon dioxide in the home can lead to a range of different health concerns, such as headaches, fatigue and even breathing difficulties.

Carbon Dioxide Versus Carbon Monoxide

Carbon dioxide, as we mentioned above, is a part of the breathing process for humans and animals.  We breathe in oxygen and exhale carbon dioxide. Plants then use that carbon dioxide and convert it back into oxygen.  It is a naturally occurring gas and has only very rarely resulted in poisoning. It may however cause a range of other health complications. Even though it may not be as deadly as carbon monoxide, carbon dioxide is still harmful, especially at higher levels.

Carbon monoxide on the other hand is created when there is an incomplete combustion of things like fossil fuels, oil, coal and natural gas.  It is not a naturally occurring gas. It is an odorless and tasteless gas and when not properly ventilated, can lead to carbon monoxide poisoning – which can be deadly if not treated immediately.

The Effects of Carbon Dioxide in the Home

Studies have shown that higher indoor CO2 levels are correlated with higher levels of other indoor pollutants. The primary source of CO2 production is the respiration of the building occupants which can result in levels upwards of 2500 ppm.  For comparison, the American Society of Heating, Refrigerating, and Air Conditioning Engineers sets the recommended limits of indoor CO2 concentration at 1000ppm.  At these levels studies have shown slower work performance, increased absence from work/ school, 11-23% decrease in decision making performance (at 1000 ppm compared to 600 ppm), detectable increases in heart rate and blood pressure, and decreases in cerebral electrical activity. Another study found that increasing CO2 by as little as 400 ppm resulted in a 21% decrease in cognitive function. 

The effects of elevated CO2 are experienced across the country everywhere from homes to schools to office spaces. One study reported that 23% of office workers experienced at least two or more symptoms of elevated CO2 in the workspace on a regular basis. Meeting rooms in particular showed levels over 1900 ppm after a 30–90 minute meeting. It is estimated that just a 20-30% reduction of symptoms would equal economic benefits of $10-30 billion. Classrooms are also a problem area, with over 45% of classroom tests reported to have above a 1000 ppm average CO2 concentration. What is worse, is that the rise in “green buildings” such as those with LEED certification has contributed to an increase in CO2 concentrations. The Boston public housing assessment found median levels of CO2 to be 809 ppm in conventional apartments and 1,204 ppm in LEED certified apartments.


Carbon Dioxide Sources in the Home

CO2 is all around you. While the level of CO2 is relatively low outdoors, it can increase significantly indoors.  Here are a few of the major causes of carbon dioxide in the home:

Humans and Pets

Think about it… You breathe in oxygen and you exhale carbon dioxide.  Your pets exhale carbon dioxide.  So, if you have more people and pets and not enough square footage, the chances of having elevated levels of CO2 in your home would increase greatly.

The Ground Beneath Your Home

Soil capping occurs when a “cap” is placed over contaminated soil. However, this process can cause the soil to swell and become waterlogged, leaving little to no room for the soil gases to escape.  This can sometimes leave the basement as the likely culprit for gases to escape through.  An example of this is houses in the countryside, especially those built on a previous farm, may have increased levels of CO2 thanks to the use of fertilizers.

Carbon dioxide naturally occurs in soil thanks to decomposition.

Kitchen & Fireplace

Any open flame creates carbon dioxide.  If you have a fireplace or gas heating stove, this will not only add to the CO2 in your home, but also results in a decrease in oxygen as the fire consumes oxygen.


Similar to fireplaces and the open flames on your stovetop, smoking cigarettes (pipes, cigars, etc.) indoors produces its own fair share of carbon dioxide.  Smoking indoors means less oxygen and more CO2 in your home.

Poor Building Ventilation

An increase in energy efficiency in buildings tends to correlate with a decrease in indoor air quality due to poor ventilation. Energy efficient buildings recirculate the same air to save on heating and cooling cost, rather than bringing fresh oxygenated air in from outdoors. Over time the CO2 levels can accumulate to well over the recommended limit. 

Sick Building Syndrome (SBS)

Indoor air quality has a huge impact on our health and productivity. Poor indoor air quality can lead to Sick Building Syndrome (SBS) which results in billions of dollars of annual loss in workplace productivity due to high rates of absence, poor work performance, and increased health care cost. SBS is caused by a variety of air quality factors including microbiological pollutants, chemical pollutants, low ventilation rates, volatile organic compounds and elevated carbon dioxide (CO2) levels. Symptoms of SBS include everything from dry eye and sinus irritation to headaches, fatigue, dizziness, coughing and shortness of breath.

Carbon dioxide is one of the major pollutants contributing to SBS.

Reducing Carbon Dioxide Indoors

Knowing that increased levels of co2 in your home could cause things like headaches, fatigue, breathing issues and even lead to an increase in respiratory infections, you may be wondering now how to reduce the carbon dioxide levels in your home and whether a carbon dioxide air purifier is right for you. Here are a few ways you can accomplish that:

  1. Consider investing in the aerium to purify the air.  The aerium is the world’s first organic air purifier that uses algae to clean the air we breathe.  As a carbon dioxide air purifier, it specifically targets CO2, whereas the majority of other air filters do not. The aerium is as effective as 25 natural air purifying plants for a fraction of the cost, time and space.
  2. Open a window. By opening a window, you help the air flow circulate and allow fresh air to enter the room and CO2 to escape the room.
  3. Limit the use of flames indoors.  That may be easier said than done if you have a natural gas stove, but by reducing the use of flames indoors, this may help maintain a good level of oxygen and lower levels of CO2.
  4. Smoke outdoors. If you smoke, you should do so outdoors as by smoking indoors you reduce the level of oxygen in the home and increase the amount of CO2.


Fisk, W. How IEQ affects health, productivity. 2002. ASHRAE Journal 44(5): 56-60.

Erdmann, CA, Steiner, K.C., and Apte, M.G. Indoor carbon dioxide concentrations and sick building syndrome symptoms in the base study revisited: analyses of the 100 building dataset.2002. Proceedings: Indoor Air

Satish, U., M.J. Mendell, K. Shekhar, T. Hotchi, D. Sullivan, S. Streufert, and W.J Fisk.  Is CO2 an indoor pollutant? Direct effects of low to moderate CO2 concentrations on human decision making performance. 2012. Environmental Health Perspectives 120 (12): 1671-1677.

Allen, J.G., P. MacNAughton, U.Satish, S. Santanam, J. Vallarino, and J.D. Spengler.  Associations of cognitive function scores with carbon dioxide, ventilation, and volatile organic compound exposure in office workers: a controlled exposure study of green and conventional office environments. 2016. Environmental Health Perspectives 124(6): 805- 812.

Azuma, K. N. Kagi, U. Yanagi, and H. Osawa. Effects of low level inhalation exposure on to carbon dioxide in indoor environments: a short review on human health and psychomotor performance. 2018. Environment International 121: 51-56.

Fisk, W.  Health and productivity gains from better indoor environments and their implications for the U.S. department of energy. 2000. E-Vision 2000 Conference. Washington, D.C.