Dishing the Dirt on Germs in Your Car28 July 2020
Do you have a habit of leaving things behind in the car? Your takeaway coffee cup or drive-thru rubbish? What about your sunglasses, receipts or loose change?
As summer continues, hot cars are the perfect breeding spot for dangerous germs. With sterile testing equipment, we swabbed 16 everyday items to show you what these lurking germs look like.
We also recorded the temperature inside the car, which reached a scorching 33°C – that’s hotter than the average summer in Greece!
Explore our results below and see what germs look like on typical items after just a few days inside a hot car.
Sunglasses and carrier bags grow more bacteria than food
Our study shows that non-food items we typically leave in the car, like sunglasses, dog toys and carrier bags, produce greater bacteria growth than food and drink packaging.
If you have a habit of leaving these items behind in your car, you may want to clean them properly after seeing our test – here’s what their germs look like.
Sunglasses contaminated with fungi can cause infection
The shape of the bacteria on our sunglasses is called a ‘rhizoid’ and indicates a type of fungi! Research suggests that glasses are often highly contaminated with the Staphylococcus epidermidis bacteria, which can cause an infection for those with weakened immune systems.
Dog toy germs linked with disease
The red germs could be Serratia marcescens, which is often found in damp conditions – like a wet dog toy. The bacteria can cause disease after entering the human body and resists common antibiotics.
Toxic mould grows on carrier bags
Our carrier bag swab test appears to have grown green mould, which is a toxic substance that can be dangerous to our respiratory health, particularly if you have asthma or allergies.
Exercise fans should avoid leaving sweaty gym gear in the car
Ever leave your trainers and kit in the car after a workout? You might want to break the habit after seeing our results.
In our study, sweaty gym clothes and dirty trainers produce significant amounts of bacteria. After just couple of days, these petri dishes produced a variety of germs, showing just how dirty our workout gear can be.
Fortunately, sweat bacteria is normally harmless, apart from the smell! Although, trainers are riskier, especially if you like running or outdoor gym classes. Another study found bacteria such as E. coli and faecal bacteria on shoes – so watch out for dog dirt.
Loose change, kids’ dummies and receipts are bad for bacteria
Other non-food items we typically leave in the car, like coins, kids’ dummies and receipts also had large bacteria growth. See how dirty these objects are below.
Coins carry life-threatening bacteria
Research by the microbiology team at the London Metropolitan University found that our money harbours life-threatening bacteria that’s linked with superbugs.
They also discovered that coins are a ‘breeding ground for harmful bacteria’ with ‘many microorganisms thriving on metal’. You can see similar results in our test, as our loose change swab has a variety of bacteria growth.
Dirty dummies linked to infection for babies
Our child’s dummy swab indicated signs of a yeast bacteria, which is common for babies who can get oral thrush. It’s normally harmless and can be treated with medicine.
Even so, you probably shouldn’t give your baby a dummy that’s been on the floor. If you find your little one has tossed their dummy away in your car, always dispose of it.
In our swab test, it seems that mould grows on our leftover shopping receipts. Mould can produce toxic substances that irritate allergies and asthma, so make sure to bin your receipts when you no longer need them.
Drive-thru treats leave mould behind
As lockdown restrictions ease, many of us are flocking back to the drive thru. But the bacteria growth from common drive-thru items might make you think twice about leaving your rubbish in the car.
Surprisingly, drive-thru packaging didn’t produce as much bacteria growth as other items. However, there was quite a variety of different bacteria types and what seems to be lots of mould.
While the bacteria on the water bottle might not seem too shocking, you should never leave a plastic bottle behind in a hot car, because plastic can release toxic chemicals in heat.
Don’t take the risk – dispose of your rubbish in the bins provided at the drive-thru or at home, and remember to recycle where you can.
What about those snacks on a long journey?
Planning a day out or a camping trip? We compared other foods you might snack on in the car during a long drive. If you have a sweet tooth, beware…
As you can see, sweets are the worst culprit, with a range of different bacteria colonies growing. Although, the packet of crisps and protein bar weren’t that far behind!
10 top tips to keep your car germ-free
If you are guilty of leaving things behind in the car, read our 10 top tips to keep your vehicle clean.
1. Have a clear out – dispose of your rubbish and tidy away anything you want to keep
2. Recycle as much as possible, including food packaging, water bottles and coffee cups
3. Remove your floor mats and clean them with hot soapy water, and then allow to dry
4. Vacuum any crumbs or dirt from the floor and on the seats
5. Wipe the windows with cleaning solution and a microfibre cloth
6. Clean the dashboard and steering wheel thoroughly with antibacterial wipes
7. Check your door pockets for forgotten items and wipe away any grime
8. Clean the handles, seatbelts and window switches with antibacterial wipes
9. Wipe down anything you might like to keep in the car, like a child’s toy
10. Keep a handy hygiene kit in the glove box, including antibacterial wipes and hand gel
Our testing method
We used labelled nutrient agar in petri dishes and sterile cotton buds to swab 16 everyday items which are commonly left behind in cars.
Hand sanitiser was applied in between each swab and the petri dishes were sealed after swabbing to avoid cross-contamination. Each seal was briefly removed to record findings after two days of exposure but was then resealed.
Items were exposed to a disinfected car for three days, after which the swabs were taken. Recordings took place at the same time as the swabs, two days and five days after the exposure period, which is the recommended length of time.
Temperature was recorded at the same time throughout the exposure and recording period. The average temperature was 29°C and the peak temperature was 33°C.
To increase the reliability of our test, we also had a labelled control test in the same conditions, which did not produce any visible bacteria.
You can see what other germs look like in our guide to child car seats, with cleaning and safety tips for parents. Don’t forget to explore the Leasing Lounge for more of the latest car news and reviews.