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Tired While Driving? This Is the Crazy Reason Why.

Have you ever wondered why long car journeys make you feel tired and sleepy? Many believe it’s due to the boring, unchanging motorways that cause the sleepiness during long-distance road trips, but perhaps it’s something else? Carbon Dioxide sensor specialists Gas Sensing Solution (GSS), conducted an experiment to test the effects of long car journeys and the level of Carbon Dioxide (CO2) on our concentration and tiredness whilst on the road.

The results revealed that a build-up of naturally occurring CO2 gas produced from breathing can increase levels of CO2 within closed spaces from normal levels of 1,000 ppm to an astounding 10,000 pp, within a couple of hours. Meaning that during long car journeys, drivers and passengers can become drowsy and lethargic.

Understanding CO2

Carbon Dioxide is a gas that is invisible to the naked eye and odorless so it cannot be detected without high-powered sensors. CO2 is naturally present in the Earth’s atmosphere and is essential for life to strive, at low levels of concentration it is expelled through our breathe when we exhale. Although CO2 is naturally occurring and essential to our lives, high levels of CO2 can be harmful to our health and in worse cases can cause brain damage and death through oxygen deprivation from extreme exposure to CO2.

Driving for long car journeys will produce a higher level of CO2 but not enough to cause brain damage or death. However, the increase of CO2 levels when driving long distances can be dangerous as it can cause sleepiness, poor concentration, loss of attention, as well as headaches, and nausea. Not really how you want to feel whilst driving at 70mph.

Statistics recorded by the American National Sleep Foundation found that 60% of adult drivers within the US – about 168 million people – said that they have driven a vehicle while feeling drowsy in the past year. More than one-third, (37% or 103 million people), admitted to falling asleep at the wheel. Of those who have nodded off, 13% stated that they had done so at least once a month. In the UK drowsy driving represents 10 to 30 percent of all crashes.

Experiment Details and Results

For this experiment, GSS used their CO2 logger on a long road trip to monitor the changing levels of CO2 throughout their journey.

Dr. David Moodie, Technical Manager at GSS, explained, “On a trip to Asia we used our CO2 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 10,000 ppm on one journey – so we decided to check the levels on a long road trip across the UK.

Before the 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 confined within a car. The engine was switched off and the windows were 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 at a normal 1,000 ppm. It then rocketed to almost 4,000 ppm in just 15 minutes! At this stage, the atmosphere inside the car had become extremely stuffy and unpleasant.

An article last year entitled Carbon Dioxide Accumulation Inside Vehicles: The effects of ventilation and driving conditions discovered that driving in a car with multiple people on a long trip can exceed CO2 levels by 2,500 ppm which can highly reduce occupants’ concentration.

The next stage was to test CO2 levels in a moving car. The first car journey involved two people traveling for an hour to a supermarket. The CO2 from their respiration increased the concentration of CO2 in the car cabin to around 1,400 ppm. Surprisingly, it only took about forty-five minutes to reach this level, which shows just how quickly CO2 levels can rise within confined spaces. The datalogger was then left in the car overnight with the windows closed. The graph shows just how long it takes for the CO2 to disperse from a closed car, taking all night, until around 9 am the next day to drop down to nearer ambient 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 2,000 ppm in about twenty minutes. This is the level where CO2 symptoms can start to cause loss of concentration, headaches, and sleepiness. 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 CO2 logger measurements how rapidly CO2 can build up in an enclosed space with several occupants – and in a relatively short space of time too.  The results on both journeys exceeded World Health Organisation guideline that CO2 levels should be below 1,000 ppm.”

The CO2 logger used in the experiment measures CO2 concentration, air pressure, and temperature, along with relative humidity every few minutes. This unit uses a CozIR-A sensor, created with leading technology to create the most efficient low power, ambient air sensor on the market. The unique LED technology on the CozIR-A sensor created by GSS allows very low power consumption, such as battery-powered CO2 monitors to be used in such devices as this logger. Able to record over 2 weeks without needing a change of battery.

Car Accident statistics highlighting the dangers of drowsy driving

The National Highway Traffic Safety Administration estimates that driving whilst tired has been responsible for “72,000 crashes, 44,000 injuries, and 800 deaths in 2013”. However, it should be stated that these numbers may be grossly underestimated, and drowsiness could have been the cause of up to 6,000 fatal crashes each year.

These figures highlight the importance of staying focused during long car journeys and keeping in mind the effects of CO2. Being mindful to open a window or take occasional pit stops during your journey can help lower the levels of CO2 in your car and help you regain your concentration whilst driving.

Naturally occurring carbon dioxide gas from our breath in confined spaces can cause drowsiness and loss of concentration whilst driving. It is especially dangerous during long distances and has been linked to many road accidents.

Written By

Lauren Hannah is the author of popular blog; Gas Sensing Solutions that investigates, invents and informs experts and the public about CO2 sensing. Her main interests centre around around CO2 in space, aviation, food, transport and health & safety. Along with researching into new inventions and the effects of CO2 on the environment and on ourselves. In her current role she dedicates her experience to educating and inspiring others about CO2 applications.

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