Typical CO2 Levels at Home Tester

CO2 Levels at home

Is there a tester for carbon dioxide?

Measuring carbon dioxide, or CO2 is the current gold standard for measuring indoor air quality in the home. In fact, many individuals measure carbon dioxide to ensure that the home is healthy and proper ventilation is in place. This is because elevated levels of carbon dioxide typically indicate that an insufficient amount of fresh, outdoor air is being delivered to occupied areas of a building.

To do this, carbon dioxide can be measured in the air using CO2 gas meters or monitors. Inside these monitors are small carbon dioxide sensors that typically use non-dispersive infrared technology to determine the amount of CO2 molecules in the air. These devices range from $50-$500. 

How accurate is a CO2 tester?

The accuracy of a carbon dioxide tester depends on the specific type and model of the device, as well as the conditions under which it is being used. 

In general, most commercially available home carbon dioxide testers are accurate within a range of +/- 50 parts per million (ppm) or better. This means that if the actual carbon dioxide level is 400ppm the CO2 tester reading could be anywhere from 350 to 450 ppm. However, it is important to note that the accuracy of a tester can be affected by additional factors such as temperature, humidity, or consistent airflow. 

Overall, while a CO2 tester is a perfect indicator of the indoor air quality, its accuracy depends significantly on the specific type of device and the overall environment.

CO2 Testers for Home Use and Indoor Air Quality

In order to measure CO2 levels in your home, you will need a carbon dioxide monitor or tester. With a CO2 tester you are able to easily and affordably measure carbon dioxide levels in your home. These devices come in several different types including handheld, desktop, or wall-mounted units. Some testers may also measure other parameters such as temperature, dew point, humidity, or volatile organic compounds.

When choosing a CO2 tester for home use, its important to consider factors such as accuracy, range, and overall ease of use. You may also want to look for a device that is easy to maintain and is easy to read; to understand the CO2 levels in real time. Additionally, you may want to consider the cost and whether the device requires any ongoing maintenance or replacement parts.

Further, in order to understand the CO2 tester analysis one should be aware of what CO2 levels are normal and what levels are above average, we highlight an easy to follow CO2 chart below

What is an acceptable level of CO2 in a home?

When it comes to CO2 levels in a home, many individuals look to the ASHRAE association which sets standards in place for recommended indoor air CO2 concentrations. Below we have included a list of CO2 levels per ASHRAE to provide guideline when you read your CO2 monitor so you can understand the levels in your home. In summary, ASHRAE recommends that levels in your home be between, maintained at, or below 1,000ppm in schools and 800ppm in offices.

CO2 Levels and your Health

 ~400 ppm  background (normal) outdoor air levels
400- 1,000 ppm  typical levels found in occupied spaces with good air exchange
1,000 – 2,000 ppm levels associated with complaints of drowsiness and poor
2,000 – 5,000 ppm

levels associated with headaches, sleepiness, and stagnant, stale, stuffy air

Poor concentration, loss of attention, increased heart rate and slight nausea may also be present

>5,000 ppm Exposure may lead to serious oxygen deprivation symptoms


Keeping CO2 levels less than 700ppm above the outdoor air concentration can be an indication that sufficient outdoor air is being brought into your indoor air environment. It is recommended to stay as close to 400ppm (outdoor CO2 concentration) and below 800ppm.

CO2 Tester Experiment 

We decided to put our indoor air quality monitor to the test and did our own CO2 levels test at home using a Aranet4 HOME. While CO2Meter is recognized as a leader in indoor air quality solutions and CO2 monitoring, we chose a friend for the test to ensure we could gain a true analysis and credible product feedback.

And we were sure to gain all of the results and analysis to share with customers to provide them with what a full day looks like of CO2 monitoring and just how much carbon dioxide someone could be exposed to every day.

After a full day using the monitor, we received the data, exported it to a text file and graphed it in Microsoft Excel. Here's what we learned.

6 a.m.

Woke up and checked the monitor. The CO2 level was 1,380 ppm with two people sleeping in a bedroom and the door closed. This is well over the National Institute for Occupation Safety and Health (NIOSH) limit of 1,000 ppm, and even over the 1,200 ppm recommended CO2 level for indoor greenhouses.

I opened the bedroom door and made a mental note that if I ever wanted to grow plants indoors, I should keep them in the bedroom.

co2 levels in home over a day

7 a.m. 

With the bedroom door open, my CO2 levels at home dropped to 650 ppm. While this is above the approximately 400 ppm fresh air level, it makes sense that in an occupied home or office the CO2 level should be higher than normal. If my CO2 levels at home were too high, it would mean I wasn't getting enough fresh air. If the CO2 level was too low, it would indicate too much fresh air and wasted HVAC energy.

8 a.m.

After some time in my home office checking email, it was time to take a morning walk. My new year’s resolution is to actually pay attention to my Apple Watch and get in 10,000 steps a day. The moment I stepped outdoors, the CM-501 dropped to 400 ppm and stayed at that level for the next hour.

9 a.m.

I decided to make a quick trip to the local Starbucks for coffee. Since it was about 70 degrees outside, I didn’t use the heater or air conditioning in the car.  However, with the windows closed, over 15 minute drive the CO2 level inside the car rose to 1,900 ppm. They immediately dropped when I opened the door and went to get my coffee, then rose again to 2,400 ppm on the trip back.

This isn’t surprising. CO2 levels in cars can rise quickly. In a study conducted by SenseAir, they found that with 4 adults in a car, the CO2 level could reach 6,000 ppm even with the fresh air ventilation turned on. This is important to know, as between 10 and 30% of all automobile accidents are attributed to drowsiness.

To combat the high level of CO2, I turned on the air conditioning. The effect was immediate, as you can see in the graph. Within 4 blocks, the cabin air quality dipped to 500 ppm.

10 a.m. - 5 p.m.

The remainder of my day was spent alone in my home office with the door open. My CO2 levels at home varied between 750 and 800 ppm.

While not shown on the graph, the CO2 level in the house began to rise on the CM-501 with two of us in the kitchen making dinner, and peaked at 1,100 ppm in the family room watching TV before bedtime.

Why CO2 levels at home matter

While my day was normal, I learned that it’s easy to be unintentionally exposed to high CO2 levels at home. This is important for everyone, but especially for students and office workers. In a study led by Harvard’s environmental health researcher Joseph Allen in collaboration with colleagues from Harvard, SUNY, and Syracuse University, they observed a direct correlation between indoor air quality and cognitive performance.

According to the study, while repetitive task performance was not impacted, certain cognitive scores were 101% higher in an office environment with a high outdoor air ventilation rate. To me, this means that in order to achieve maximum productivity, I need to keep watch on CO2 levels in my home office in the future. Fortunately, simply keeping the door open works for me.

The other reason CO2 levels at home matter is that carbon dioxide levels are considered by many heating & cooling experts to be the "canary in the mineshaft."

As CO2 levels rise, the quantity of volatile organic compounds (VOCs), odors and micro-organisms in the air rise too. That’s why HVAC engineers use carbon dioxide monitors like the CM-501 to regulate airflow in modern office buildings. The same goes for private homes too.

Were my CO2 levels typical for any home?

Perhaps not. It was 70 degrees all day, the windows were shut, and neither the furnace or air conditioner turned on. The "tightness" of a house (old vs. new windows, etc.) makes a difference too.

However, the experiment was still interesting, and I'm glad I tried it. Since CO2Meter makes low-cost indoor air quality meters, it is easy for anyone to test their home's indoor air quality.

Best CO2 testers for Indoor Air Quality

There are several CO2 testers that are well suited for measuring indoor air quality in homes, classrooms, and office buildings. Here are just a few options you can consider:

  1. Aranet4 HOME Indoor Air Quality Monitor
  2. TIM10 Desktop CO2, Temp, & Humidity Monitor
  3. cSense Large Character Wall CO2 Monitor 
  4. Portable CO2 Detector and Alarm 
  5. CO2, Temp, and RH Indoor Air Quality Monitor

It's important to note that while there are many different CO2 testers available, each with its own features and capabilities - the best option for you will depend upon your use case, environment, and budget.

10 Tips to Lower CO2 Levels in Your Home

Due to our shocking experiment results of home CO2 levels, we of course wanted to research what we could do to lower CO2 levels.

Below we highlight the top 10 tips we discovered.

  1. Ensure that your HVAC is working properly (replacing your air filters can lower your CO2 levels)
  2. Design your home to support airflow (by moving large furniture away from windows and creating a open space you can ensure optimal airflow)
  3. Limit open flames (smoke releases large amounts of CO2)
  4. Incorporate plants in your home (plants help purify the air)
  5. Invest in a air purifier
  6. Increase airflow while cooking (turning on an extractor can expel CO2)
  7. Use natural cleaning agents and non-toxic paint
  8. Watch your home's humidity levels (most CO2 monitors will include this, and the average humidity level should be between 30% and 50%)
  9. Minimize rug use (pollutants can easily get trapped)
  10. Get a low-cost CO2 Monitor (like this one)

For more information regarding indoor air quality, carbon dioxide solutions and your home or workspace - contact us today.

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