Your car would be dirtier than your toilet bowl. In any case, this is what the team of microbiologists from the University of Aston (United Kingdom) commissioned by Scrap Car Comparison to assess the cleanliness of our vehicles.
Their study consisted of comparing samples taken from two toilet bowls with samples taken from different locations in five passenger vehicles. The researchers specify that the vehicles studied had all been purchased used and were between 2 and 17 years old. As for the toilets used for comparison, they had intentionally not been cleaned and had been used during the 24 hours preceding the samples (source 1).
A significant number of fecal bacteria
The analysis of the samples showed that all the cars contained fecal bacteriaand this, in much greater quantities than on toilet bowls.
Beyond faecal bacteria, scientists have also discovered a whole host of “friendly” microorganisms on board vehicles:
- Bacillus subtilis bacteria,
- pyocyanin bacilli,
- Rhodotorula yeasts,
- or even Escherichia coli.
Note: the study shows that the older the vehicle, the greater the number of bacteria found on board.
Steering wheel, seats, trunk… choice locations…
According to the samples taken in each of the vehicles, the palm of dirt goes to the trunk. Scientists discovered nearly 1,425 bacteria there. For comparison, it is estimated that a toilet bowl contains around 200 bacteria.
The driver’s seat comes second, with 649 bacteria detected. follow the gear lever (407 bacteria), the back seat (323 bacteria) and the dashboard (317 bacteria).
What about the steering wheel? Curiously, it is the element that does best, with “only” 146 bacteria. A result that scientists attribute to the massive use of hydroalcoholic gel since the start of the Covid-19 pandemic. “Due to the increased use of disinfectants since the Covid-19 pandemic, driver contact surfaces generally did not have the level of bacteria we expected,” says Dr Jonathan Cox, senior lecturer in microbiology in charge of the study.
How often should we clean our vehicles?
“This study showed that people could definitely do more to keep their cars clean. Ultimately, it’s about mitigating the risk of getting sick. We’re unlikely to eat food in the trunk of our car, but we often eat food in the driver’s seat. Washing hands before eating in this environment is a good ideaand knowing where microorganisms may be residing can help us think more about our habits when driving.”
And to conclude: “To be clear, people do not get sick every time they get into a car. There’s no need to worry too much“. But vacuuming or disinfecting once in a while won’t hurt you!