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The Car Interior Microbiome: Gas Station As An Infection Control Hotspot

Keith Warriner
November 07, 2017



When we get into our cars there are several things that go through our minds from the expectant traffic jams, price of gas through to if the hills of Scandinavia actually smell like the spruce tree air-freshener hanging from the mirror. What we don’t normally think about is the possibility of acquiring infectious microbes along our drive. The risk of infections increases with presence of the microbe, opportunity and exposure time. With regards the latter, if statistics are correct, we spend an average of 90 minutes in our cars each day that equates to 6 months per lifetime. There are also ample opportunities for infectious agents to be taken into the body when we consider what we get up to in our cars. We eat, drink, rub our eyes, touch our lips, in addition to other activities, with an increasing number living in their set of wheels. So the question is posed, can we find infectious microbes in cars and if so, where would they come from?


Microbiome of the car


Reported studies have revealed that the interior of cars harbor a diverse range of Gram positive and negative bacteria that includes clostridia and opportunistic pathogens. Staphylococci were found to be the dominant microflora with 40% of car interiors testing positive for S. aureus that included the clinical significant MRSA (Stephenson et al. 2014). The highest carriage of bacteria is to be found on the steering wheel and gear shift with the mirror adjustor being the least contaminated.  Microbes are not restricted to frequent touch surfaces and can be readily spread throughout via the air conditioning system (Sattar et al. 2017).  Interestingly, other studies have suggested that the interior of taxis and rental cars harbor a lower number of microbes compared to domestic vehicles despite the number of people frequenting them. Cars used in ride-sharing services (e.g. Uber) are thought to have the highest microbial loading due to the number of people passing through coupled with infrequent sanitation (Baskas, 2016). It would be assumed that the diversity and types of microbes encountered within car interiors would be a function of the various inputs be it from the driver, fellow passengers, shopping, pets or our rowdy friends we ferry about from a night out. Here we will consider what we can pick up from the gas station.


Visit to the gas station


gas-station-pumpThere were times when a visit to the gas station was a sedentary exercise where a bell would ring as you enter the forecourt and an assistant would come out to fill your car before giving the screen a wash. Those 1950’s nostalgic visions have long gone. Now it is all self-service which means handling the gas pump which has been touched by many hands before. In a study performed by Gerber & collegues (reported by Anon, 2015) it was found that gas pump handles harbored 3.5 million bacteria/sq (0.5 million per cm2) primarily composed on Gram-positive rods and cocci. You may think by paying at the pump you would be spared contact with the cashier but it was found that the button key pad was equally as contaminated as the gas pump handle.




gas-station-washroomWhen on a road trip the call of nature arrives and have to venture into the gas station washroom. There have been numerous studies performed on what pathogens can be acquired in washrooms with norovirus, Salmonella and hepatitis A being examples. The question is posed is if those gas station washrooms are any worse than other public connivances. There have been no official studies although it is considered that gas station washrooms rate as the worst encountered, yes even worse than coach stations. Gas station staff don’t see washrooms as a priority and in some ways, patrons don’t have the expectation of being greeted by an assistant with warm towels & perfume. Therefore, the reputation of gas station washrooms is one of poor sanitation along with empty soap and towel dispensers. Therefore, many travelers would bypass the wash stations and bring microbes straight back to the car.


Gas station drink stations


gas-station-hygiene.jpgGas stations have become mini-malls with all kinds of items for travelers to buy. The worry isn’t with the rows of jerky that are celebrating a year in store but more the ice machines at the soft drink stations. Ice machines are notorious hot spots for contamination and the gas station staff are likely too busy to maintain the units. There are no reports on the microbiological status of ice from gas stations and so we decided to go on a sampling trip to the station down the road. Sure enough the collected ice tested positive for coliforms (121 cfu/100 ml). In the context of the car microbiome, it is easy to envisage that we inevitably spill the soft drink as we place it in the cup holder thereby encouraging biofilm formation to add to the microbial community.


Sanitation in the car


There is a large knowledge gap on the degree to which infectious agents can be transferred to the car interior to ourselves. Some European gas stations consider the transfer of microbes from gas pumps sufficient that the provide disposable gloves to patrons. Maybe a better approach will be to sanitizer our hands after finishing our business at the gas station and before entering our cars. Sanitizing the car interior is a further approach although unfeasible given most of us think going through the car wash is an inconvenient task.


Further Reading


  • Anon (2015). Gas station germs; Guzzling Grime by the Gallon?
  • Baskas, H (2016) Dirty driving: Ride-hailing services worst culprits for germs, study says
  • Bren Y (2017) Car-dwellers rising: life on the curb of Canada's most expensive city
  • Sattar, S. A., B. Zargar, K. E. Wright, J. R. Rubino & M. K. Ijaz (2017) Airborne Pathogens inside Automobiles for Domestic Use: Assessing In-Car Air Decontamination Devices Using Staphylococcus aureus as the Challenge Bacterium. Applied and Environmental Microbiology, 83, 275-282.
  • Scott, J. (2015). Why are gas station restrooms so bad?
  • Stephenson, R. E., D. Gutierrez, C. Peters, M. Nichols & B. R. Boles (2014) Elucidation of bacteria found in car interiors and strategies to reduce the presence of potential pathogens. Biofouling, 30, 337-346.



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