High CO2 Levels in Your Car Leads to Drowsy Driving

drowsy driving

How much time do you really think it takes before the carbon dioxide (CO2) levels in a car can become too 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 CO2 diminish cognitive abilities, reduce response times, and impair the ability for an individual to make strategic decisions.

drowsy driver

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

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.

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 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.

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

Testing CO2 Levels in a Car

We gained insight into high CO2 levels and their effects on drivers from a study by our sensor partner Gas Sensing Solutions.

GSS recently took their CO2 data logger on a road trip to discover just how levels effected an individual and the overall affects due to the IAQ.

Dr David Moodie, Technical Manager at GSS, explained, “This follows on from a trip to Asia where we used our CO2 data logger to measure CO2 gas levels on planes, trains and taxis. We were surprised that levels were the worst in taxis – peaking at an astonishing 10000 ppm on one journey – so we decided to check the levels on our own road trip in the UK.”

"Before the data logger took to the road, it was first used to test CO2 levels in a stationary car. This would show the impact on CO2 levels with a group of 4 people in a confined space. The engine was switched off and the windows kept closed to avoid any flow of fresh air inside the vehicle. The data logger showed that when the passengers got inside the car, the CO2 level was 1000 ppm. It then rocketed to almost 4000 ppm in just 15 minutes. At that stage, the atmosphere inside the cabin had become extremely stuffy and unpleasant."

"Next came the road trip. The first car journey involved two people traveling to the supermarket. The CO2 from their exhaled breath increased the concentration of CO2 in the car cabin to around 1400 ppm. It took about forty-five minutes to reach this level. The data logger was then left in the car overnight with the windows closed. The graph taken from the data logger then displayed just how long it can take for the CO2 to disperse from a closed car, taking until around 9am the next day to drop down to nearer ambient or "normal" levels of CO2."

"The second car journey recorded four people traveling non-stop from Wales to Scotland. With four people, the level of CO2 shot up even faster, reaching 2000 ppm in about twenty minutes. This is the level where CO2 symptoms can start to cause loss of concentration, headaches and sleepiness for example. Fortunately, they opened the windows to bring in fresh air from outside, which reduced the CO2 to more acceptable, ambient levels within an hour."

Dr David Moodie added, “Our real-world data logger measurements show how CO2 levels can rapidly build up in an enclosed space with several occupants – and in a relatively short space of time too.  The results on both journeys exceeded The World Health Organization* guideline that CO2 levels should be below 1000 ppm.” 

What can you do to prevent drowsy driving?

Automobile re-circulation button

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 an open window to let in fresh air. This simple change can improve the reaction time of drivers and lower the likelihood of accidents.

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

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.

The problem is that while the recirculate feature can be useful, using it for even short periods can lead to high levels of CO2 in an enclosed truck or auto.

More Drowsy Driving Studies

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 the IAQ Mini while driving back and forth to the office.

The IAQMini is an easy to use, wireless desktop IAQ monitor that is convenient to monitor CO2 levels on-the-go.

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!


Photo by Samuele Errico Piccarini on Unsplash

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