Gas Sensing Solutions Investigates Levels of CO2 on Car Journeys

Ever wonder why long car journeys make you feel tired and sleepy? Is it the boredom of endless, never changing motorways or perhaps something else? Researchers from Gas Sensing Solutions (GSS) theorized that a build-up of carbon dioxide is the culprit, because at levels of 1,000 ppm and above people can become drowsy and lethargic. To explore this link, the researchers used a GSS gas sensor to find out how CO₂ levels changed throughout the journey.

During a recent trip to Asia, GSS engineers used the datalogger to measure CO₂ gas levels on planes, trains and taxis. The highest levels — peaking at 10,000 ppm on one journey — were documented in taxis, prompting an evaluation of gas levels during a road trip in the U.K.

The instrument was first used to test CO₂ levels in a stationary car to show the impact on gas levels with a group of four 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 datalogger showed that when the passengers got inside the car, the CO₂ level was 1,000 ppm. It then rose to almost 4,000 ppm in just 15 minutes. At that stage, occupants reported that the atmosphere inside the cabin had become stuffy and unpleasant.

The first car journey involved two people traveling to the supermarket. The CO₂ from their exhaled breath CO2 levels recorded with a datalogger. Source: GSSincreased the concentration of the gas in the car cabin to around 1,400 ppm. Surprisingly, it only took about forty-five minutes to reach this level, which shows how quickly CO₂ levels can rise. The datalogger was then left in the car overnight with the windows closed. As shown on the graph, the environment took until around 9 a.m. the next day to drop down to near ambient levels of CO₂.

A second car journey recorded four people traveling non-stop from Wales to Scotland, during which the level of CO₂ increased even faster, reaching 2,000 ppm in about 20 minutes. This is the level where CO₂ symptoms can start to cause loss of concentration, headaches and sleepiness. The travelers opened the windows to bring in fresh air from outside, which reduced the CO₂ to more acceptable, ambient levels within an hour.

During both journeys, the concentrations exceeded the World Health Organization guideline that CO₂ levels should be below 1,000 ppm.