High CO2 Levels in Your Car?

CO2 Levels and Carbon Dioxide Monitoring

How much time do you really think it takes before the Carbon Dioxide (CO2) levels in a car can become to high? The answer may be hard to believe.

According to a study conducted by Swedish sensor manufacturer Senseair, the results showed that with 4 adults in one car, CO2 levels reached 1,000 ppm in 1.5 minutes, 2,500 ppm in 5 minutes, and a shocking 6,000 ppm after 22 minutes - even with fresh air ventilation turned on!

Every wonder why you might suddenly feel tired behind the wheel?

Numerous research studies have shown that high levels of Carbon Dioxide diminish cognitive abilities, reduce response times, and impair the ability for an individual to make strategic decisions.

Drowsiness also accounts for between 10%-30% of all automobile accidents yearly, and high CO2 levels are known to be a cause.

But what does this mean for the average driver?

Best practices would dictate that short drives with a lot of passengers or long drives with few passengers should all include a cracked or open window to let in fresh air. This simple change can improve the reaction time of drivers and lower the likelihood of accidents.

A 2016 USA Today study showed 10-20 police K-9 deaths per year due to a lack of proper ventilation and high CO2 levels in police vehicles.

The use of CO2 sensors inside cars is a sure way of controlling the ventilation and even saving lives.

Changes in education and knowledge about the health effects of CO2 in enclosed spaces like cars have forced a dramatic change in the design and manufacturing of automobiles. Hyundai, a renown automobile manufacturer even offers a CO2 sensor-controlled ventilation system in all Genesis models since the 2015 model year. 

Hyundai engineers clearly agree that elevated carbon dioxide (CO2) levels created by occupant respiration inside the vehicle cabin will cause drowsiness and slow reaction times. When the sensor in the Genesis detects CO2 levels above 2,500 parts per million, it triggers the climate-control system to bring in more fresh air from outside the cabin.

Were Hyundai engineers ahead of the trend? We did some research and discovered that while drowsiness accounts for a large portion of automobile accidents most people are not aware of the importance of continually recirculating fresh air into their automobile.  

Automobile re-circulation button

Did you know, that most cars have a “recirculate” button as part of the climate controls?

It's true. This feature recirculates the auto cabin air instead of bringing in fresh air. It may be used to more quickly cool or heat a cars interior, or it may be used to keep odors and dust outside the car from entering into the cabin.

While the recirculate feature can be useful, using it for even short periods can lead to high levels of CO2 in an enclosed car.

SAE International published a paper titled, "Modeling CO2 Concentrations in a Vehicle Cabin" in which they documented the quick rise in CO2 levels in a passenger car cabin. Their data showed that CO2 levels can rise above 5,000 ppm with the ventilation in re-circulation mode.

In an article titled "The Drowsy Driving Switch", Air Quality Consultant Dale Walsh recorded CO2 levels in a pickup truck rose quickly when the ventilation was set to re-circulation mode.

Automobile manufacturers are aware of this data too, and that's why modern automobile cabins are engineered to continually provide enough fresh air to keep CO2 levels at or below 2,500 ppm for a single passenger. However, by turning “recirculate” on, the constant flow of fresh air is diminished, and CO2 buildup results.

Our CO2Meter technicians tested our own vehicles utilizing CO2Mini CO2 Monitor while driving back and forth to the office.


The CO2Mini is powered via USB, so it is easy to plug into the car's USB port. Cars without a USB port used a standard USB accessory plug.

For engineers and automotive experts CO2Meter also offers the Senseair Sunrise 1% CO2 Sensor for easy integration, accuracy, precision and vibration resistance in automobile applications.

While high levels of CO2 in an enclosed car will never reach physically dangerous levels, they can have an impact on driver alertness.

Common sense dictates using the the recirculate feature on your car for only short periods of time, especially if you do not have a CO2 sensor on hand.

For more information in regards to overall Carbon Dioxide (CO2) levels and automotive applications, speak to an expert today!


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