eating in the drivers seat
12
Anthony Madaffari5 Feb 2022
NEWS

New study reveals inside of your car is dirtier than the average toilet

Do you think you know exactly how clean the inside of your car truly is? The results of this latest study should have you worried.

A new university study commissioned by Scrap Car Comparison has revealed that the inside of our cars have significantly higher levels of bacteria on them than the average toilet. Yuck!

Researchers at Aston University’s School of Biosciences in the UK took samples from a selection of car interiors with varying ownership histories, to establish bacterial contamination levels within the cars, and to highlight just how thoroughly people actually clean them (or not). Despite the newest car tested in the study being only two years old, the results revealed that motorists should be cleaning the inside of their ride a lot more than they currently do, with harmful bacteria likely to be found in most cars out on the road today.

lab 03
lab 04

For the study, samples were taken by swabbing several locations within five used cars using a sterile cotton bud swab, hydrated with phosphate-buffered saline. Each swab was spread onto a Nutrient Agar (NA) and a Violet Red Bile Glucose (VRBG) culture medium. NA supports all bacterial growth, whereas VRBG only supports the growth of?Enterobacteriaceae (faeces).

Vehicles sampled in the study were:

  • Peugeot 307-SW; 17 years old; animals; bought second hand with one previous owner
  • VW Golf; 5 years old; animals and children; bought third hand with two previous owners
  • Ford Focus; 13 years old; animals and children; bought second hand with one previous owner
  • Honda Jazz; 9 years old; animals and children; bought third hand with two previous owners
  • Peugeot 308; 2 years old; bought second hand with one previous owner

1f dashboard 02
2e car boot 02
4c drivers seat 02

For the comparison, two domestic toilets were chosen that had not been knowingly cleaned but had been used in the preceding 24 hours.? 

A particular area of significantly high levels of bacteria was found to be in the car’s boot, which played host to E.coli, commonly known as faecal bacteria. It was also found on the driver’s seat. The findings pose a clear concern for anyone who puts their fruit and vegetables in the boot after a trip to the supermarket or enjoys a drive-thru dinner in the driver’s seat. 

carboot2 h4oz

Beyond the boot and driver's seat, the other areas tested included the gearstick, dashboard and backseat which also saw higher levels of bacterial contamination than is found on, or even inside, the average toilet. The bacteria found included Pseudomonas, a bacterium with strains that can’t easily be treated with antibiotics and Staph Aureus, a germ associated with coughs and sneezes that in some cases is linked to MRSA. 

The filthiest areas of a car 

Car boot - 1,425 bacteria identified
Driver’s seat - 649 bacteria identified
Gearstick - 407 bacteria identified
Back seat - 323 bacteria identified
Dashboard - 317 bacteria identified
Steering wheel - 146 bacteria identified

There was also a correlation discovered between the age of a car, and the levels of bacteria likely to be found within it. The older cars sampled for the study exhibited higher bacteria loads than those that have been on the road for a shorter amount of time. 

car cleaning 1

However, the study did highlight some good news for drivers, as the researchers found that out of all areas within our cars, the steering wheel is generally the cleanest. This high-contact area saw very low levels of bacterial contamination, which is potentially thanks to the uplift in hand sanitiser use following the COVID-19 pandemic. 

This is a big shift compared to a similar study pre-COVID which found that a car’s steering wheel had four times the level of bacteria than a toilet seat. Keep up the hand sanitising folks!

car cleaning 2

Dr. Jonathan Cox, Senior Lecturer in Microbiology at Aston University said that the results of the study were fascinating, as they help to show that despite cleaning our cars, the older they are, the dirtier they generally become. 

“This becomes key when thinking about areas such as the trunk or driver’s seat. Many of us have placed loose groceries in our trunk, or dropped the odd crisp onto our seat, before picking it up and eating it.

carboot1

“These results however highlight that we should instead change how we think about our cars and cleanliness. Often, we will clean our cars based on whether they ‘look’ clean versus whether they actually are clean, but you would never even think about eating off of your toilet seat.

“Upholstery, in particular, should be given deep clean and I for one will always clean any used car I buy in the future myself!”

This is a timely reminder to maybe set aside an hour this weekend to give your car a thourogh clean on the inside. Here are some tips to get you started.

Related: What are the best car cleaning hacks and tips?
Related: Hygiene when driving
Related: How to clean your car with a pressure washer
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