High carbon dioxide (CO2) levels in homes, apartments, classrooms, and workplaces like office buildings can be hazardous to occupants. The challenge for many is that they are not clear on what is considered a high CO2 level, how to measure it and how to mitigate it.
Organizations like the U.S. Green Building Council, the Occupational Safety and Health Administration - OSHA, and the Center for Disease Control - CDC are working to provide an adequate amount of data surrounding the importance of monitoring CO2 levels indoors, and what the potential long-term effects of exposure are for individuals exposed to higher amounts of CO2.
Many individuals tend to be surprised when it comes to understanding the importance of carbon dioxide monitoring and recognizing the direct impact high CO2 concentrations can have on their overall well-being, health, and cognitive skills.
Why measure CO2 indoors?
Have you ever been in a meeting after lunch, and felt groggy or unfocused? Feeling like you will barely make it through the remainder of the day, making your way into the breakroom for another coffee or energy drink? This might have more to do with CO2 levels and less to do with the after effects of a full stomach.
A study published by Lawrence Berkley National Laboratory notes that, “People produce and exhale carbon dioxide (CO2) as a consequence of their normal metabolic processes; thus, the concentrations of CO2 inside occupied buildings are higher than the concentrations of CO2 in the outdoor air.” The ill feelings, tiredness, lack of focus, and even nausea can be attributed to higher CO2 levels as our bodies go through its natural processes. Indoors, this can lead to sick building syndrome.
According to EPA.gov, “The term sick building syndrome is used to describe situations in which building occupants experience negative health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified.” Higher CO2 levels indoors bring on many of the same symptoms defined in sick building syndrome. On the contrary, monitoring CO2 indoors has been stated to dramatically reduce these specific illnesses.
Safe CO2 Levels Indoors
The word “safe” can be used to mean either “best” or “potentially harmful.” What’s important to note is that CO2 is natural. Except in levels above 3-5% it is not a dangerous gas.
Best Indoor CO2 Levels
CO2 levels indoors should be as close to 400 ppm (outdoor CO2 concentration) as possible, and no more than 700 ppm above outdoor air. If the threshold is exceeded, additional fresh air should be added to renew the air.
Not that while this was the most recent mention of CO2 levels in the 1999 ASHRAE Standard 62, it has since been removed in the 2004 version. A more accurate understanding of the ASHRAE position on CO2 is available here (pdf). They state that the fresh air flow per person should be anywhere from 5-60 cubic feet per person per minute depending on the use of the area.
However, as a rule of thumb, a maximum CO2 level between 1,000 ppm and 1,100 ppm indoors is a good goal for any home, office or classroom.
Potentially Harmful CO2 Levels
Technically, anything above the “safe” CO2 levels indoors indicates a problem with fresh air flow, not high CO2 levels per se. However, numerous studies over the years have found a direct correlation between high CO2 levels indoors (as the result of lack of fresh air) and high levels of mold, dust, bacteria and viruses in the air. In addition, high levels of CO2 correlate with increased drowsiness and lower cognitive ability.
The problem with a mechanical definition of air flow indoors is that it doesn’t help occupants who are attempting to monitor indoor air quality in their home, office or classroom. Instead, CO2 monitors are an inexpensive alternative that provides a snapshot of air quality that can be used to determine if further mitigation is needed.
Again, as a rule of thumb, CO2 levels above 1,200 ppm indoors indicate potential air flow issues, while CO2 levels above 2,000 ppm have been shown to increase occupant complaints of room “stuffiness” as well as statistically higher levels of negative respiratory effects.
How do I fix high CO2 levels in my house?
It’s important to know how to discern whether your building has poor indoor air quality. This can be done by using CO2 monitors to take readings of your home.
For instance, devices like CO2 indoor air quality monitors work great for maintaining peace of mind and having a device to indicate when ventilation is required or the need to open a window is vital.
Additionally, If you notice you become tired frequently, nauseated, or suffer from constant headaches or bodily discomfort – you should check the CO2 levels.
Additional guidelines to aid in improving indoor air quality are as follows:
- Open a nearby window, or doors to allow ventilation
- Avoid using irritants and pollutants like aerosols, perfumes, or plugins
- Add live plants to your workspace or home
- Take breaks often by stepping outside for fresh air
- Repair or upgrade HVAC systems
- Purchase air purifiers to reduce particulate matter or contaminants
Carbon Dioxide Monitoring is Important
To provide further perspective, the staff at CO2Meter frequently receives e-mails from customers who have implemented CO2 monitors into their indoor space and are surprised by the reading their new CO2 meter has indicated.
They've found that high CO2 levels indoors can have a direct impact on their quality of life. Here are some examples we would like to share:
High CO2 levels indoors in the workplace
V. Jakimov writes, “The moment I powered the TIM10 CO2 monitor a high CO2 level alarm sounded. My CO2 was around 2,800 ppm! I was a bit surprised at first but then realized that my small office gets filled quite fast with breath exhaust carbon dioxide (CO2).”
In a paper published in the journal Environmental Health Perspectives, researchers found that people working in buildings with below-average indoor air pollution and carbon dioxide showed better cognitive functioning than workers in offices with typical VOC and CO2 levels.
Fall asleep at home watching movies
Stephen L. writes, “My friends and I have been surprised at how quickly CO2 builds up in a room full of people. In a basement home theater setup I installed, with six people in a 20’x 20’x 8’ room watching a 2 hour movie, the CO2 concentration went from 400ppm to 2,000ppm by the end of the movie.”
Children sick, tired at school
Ken. C., a science teacher writes, “In one classroom of 30 students after lunch reached CO2 levels of 4,825ppm with the door closed...We noticed a rise in asthma sufferers needing their inhalers later in the day when CO2 levels were the highest, typically after lunch.
We also found a direct correlation to nausea, and headache complaints when levels were over 2,000ppm.
Yawning started about 2,500ppm and progressed to some students just laying their heads down around 3,500ppm."
According to the EPA, indoor air quality (IAQ) directly impacts student academic performance and health. For example, the Chester School District in Connecticut saw the number of asthma-related health office visits decrease dramatically – from 463 to 256 – in a single year after improving the air quality in their schools. The Hartford school district saw asthma-related incidents decline from 11,334 to 8,929 in one school year.
Tired while driving
David R. writes, “Our studies found carbon dioxide levels rise to over 3,000ppm from 400ppm (outdoor air) in 30 minutes in an enclosed automobile with a single passenger.”
In fact, studies show that drowsiness accounts for between 10% and 30% of all automobile accidents and high CO2 levels are known to cause drowsiness. As a result, high-end auto manufacturers now put CO2 sensors in in their car cabins to automatically add fresh air when needed.
Lower concentration in the morning
A study by the military in South Korea attempted to determine the effect of CO2 levels in sleeping barracks on soldiers shooting accuracy. Two platoons of recruits were put in separate barracks: one with the windows and vents open, the other with them closed. After a full night sleep, both platoons participated in shooting accuracy tests.
The military was surprised to discover that the soldiers who slept in well-ventilated barracks had statistically improved shooting accuracy. In fact, they were so surprised that they switched the platoons the second night, repeated the tests, and found that the platoon in the well-ventilated barracks performance improved, while the other platoon’s performance suffered.
Dissolved CO2 Leaching from Soil Can be Harmful
Can CO2 leaching from the soil be harmful to homeowners? We ask an expert to find out.
It started when we received a call from a customer who claimed that every time it rained, the pilot light on his furnace went out, and he got so sick he was unable to leave the house. An HVAC specialist determined it was CO2 in the basement. We asked Keith Volsted, President of VSI Environmental in Ingleside, Illinois for some fact on the subject.
CO2Meter: Keith, is their carbon dioxide hidden in the ground around our homes?
Keith: CO2 in soil typically comes from natural decomposition. I have encountered several homes with elevated CO2, all built on farm land. Manure, fertilizers, nutrients are all added to the soil to enhance crop output. These products can combine and break down over time to create naturally occurring CO2 or soil gas which can be sucked or drawn into a home.
CO2Meter: So is the CO2 being pushed into the basement?
Keith: Rarely will you find soil gas pushed into a home. Ground water tables rise very slowly, so they are unlikely to have a big impact except in rare cases. What does happen when it rains is soil capping, where the rain causes the soil to expand and tighten up not allowing soil gas to escape into the air around a home. At the same time, depending on the type of foundation the home may have, outside air that might penetrate dry soil below the foundation is cut off.
Surprisingly neither of these things alone causes the soil gas to enter the home. It is the home itself that is the driving force that literally sucks the soil gas from the ground.
CO2Meter: So you’re saying CO2 isn’t being pushed in – it is being drawn in?
Keith: It is called the “Stack Effect” – warmer air rising, mechanical exhausts such as bath fans, clothes dryers, range hoods, furnaces and water heater exhaust all contribute to less air in the home than in the ground, it is this difference in pressure that draws the soil gasses into the home.
CO2Meter: So the simple solution is just to put a fan in a basement window, right?
Keith: Installing a window fan in a basement window that sucks basement air out only depressurizes the area more. Blowing fresh air into the basement would have a far greater impact on reducing soil gas entry; however this is not always practical year round. A far better approach is to address the problem at the source, the soil itself.
CO2Meter: What do you mean?
Keith: The process is known as soil depressurization. It is a common approach to radon gas reduction, also a soil gas. By sealing sump pits, large cracks and openings in the foundation, and creating a negative pressure below the foundation just strong enough to overcome the normal air pressures in the home, soil gases of all kinds can be collected and safely discharged outside, creating a healthier home and in most cases a dryer basement.
Ensuring Improved Indoor Air Quality
While it is obvious that high carbon dioxide concentrations cannot explain every sickness, it is worth considering. Just beginning the discussion around indoor air quality can be as simple as sharing an email with resources to approaching the topic alongside colleagues with enthusiasm rather than criticism.
Encouraging changes like implementing a Indoor Air Quality CO2 Monitor, adding live plants and opening windows will allow others to see immediate benefits reducing fatigue, optimizing performance, and gaining back productivity in the workplace.
For more information surrounding indoor air quality solutions, contact us today.