How to effectively clean the inside of your car if you’re worried about COVID-19

If the coronavirus outbreak has you cleaning up against bacteria and viruses, your car can prove a real challenge. It has lots of fussy nooks and crannies, all crammed into a closed space shared by multiple people. I recently showed you some new tech that will use ultraviolet light to keep cars sanitary, but in the meantime let’s go after germs in your car with solutions we have right now.

See the latest coronavirus information from the CDC here.

A dangerous disinfectant

There’s one powerful car disinfectant I can’t even demonstrate since I’m based in California where it’s banned: An ozone-generating machine. It generates colorless O3 ozone gas, different from the more common O2 that makes up about 20% of the air we breathe. That third oxygen molecule in ozone loves to break off and interact with microbes (including viruses) in a way that destroys them. 

The problem is that the concentration of ozone needed to kill germs and viruses also damages lung linings and other mucous membranes, which is why California banned ozone generators in 2009. It isn’t just a California “nanny state” thing: The federal EPA also concludes that ozone can damage your lungs when present at concentrations effective against microbes. You’ll see lots of ozone machines available online, but I’d advise you to avoid them for personal use.

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Removing viruses and bad smell from your car

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Sprays and liquids

That brings us to cleaning liquids and sprays. The owner’s manual for my Crown Vic disallows almost every cleaning solution other than a damp rag, and your car’s manual probably says the same. Bearing that in mind, and leaving the final decision to you, let’s get real and see what you have under the sink that claims to kill 99.9% of bacteria and viruses.

The active ingredient in many spray cleaners is sodium hypochlorite, which is household bleach. A spray cleaner probably has around 2% concentration of bleach, compared to a bottle of common household bleach with a 6% concentration, but it’s still there. Bleach is a great disinfectant, but one that I’d hesitate to use on my car’s interior finishes. It just seems too harsh, especially over time and repeated uses. On places like rear cargo mats, door scuff plates and other tough trim, it could be an option, so I’ll recommend it conditionally.

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Popular sterilizing wipes that contain sodium hypochlorite, or household bleach.

Many other consumer cleaners use benzylkonium chloride, also sometimes listed as benzylammonium chloride, as their active ingredient. They’re still probably in violation of your car’s owner’s manual but appear to be gentler than bleach. BKC/BAC is a recognized disinfectant and some studies suggest it works better than the alcohol-based hand sanitizers that we’re slathering on lately.  

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Formula 409 is also made by the Clorox company, but doesn’t use bleach as its active ingredient, using benzylkonium chloride instead.

The EPA has published a list of cleaning products that are registered for use against the coronavirus that causes COVID-19. There are other products that use the same active ingredients we’ve discussed, but choosing a product from this list may give you extra peace of mind — assuming you can find any of them in stock.

Whatever you use on car surfaces, read the directions and note how much contact time it requires to kill germs and viruses. A quick wipe is just antiviral theater. The product’s fine print may surprise you, with recommended “wet times” of anywhere from 30 seconds to 10 minutes.  

Note that these products could affect the supple, moist-looking, deep color most of us value on our car’s interior surfaces. That’s why the owner’s manual advises against them, but you have to judge the risk to the interior finishes vs. the risk from people who are in your car.

Where to clean

Carefully cleaning your car’s interior can be a big chore — ask any auto detailer who gets paid a lot of money to do so — but you can simplify the job by focusing on these 12 hot spots. It’s a lot, but it’s better than the overwhelming task of disinfecting the entire interior.

• Key and remote fob
• Exterior door handles, both sides
• Trunk lid or liftgate grab area
• Interior door pull, both sides
• Start button, if equipped
• Rear view mirror, back and edges
• Vents
• Gear selector
• Center stack knobs, buttons and screen
• Seat belt and buckle (avoid harsh cleaners on the belt itself, lest they degrade the fibers and the belt’s strength)
• Parking brake release

The screen is a tricky area: It gets touched a lot, but it’s a bad place to use any kind of serious cleaner. Use screen wipes, which aren’t anti-microbial, and use your voice more often!

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Screen cleaning wipes whose only anti-microbial function is physical, not chemical. But screens demand special care, even though they are highly touched.

Disinfecting the air in your car

Few of us drive with the window down than we did in years past, so your car’s HVAC system is at the center of everything you breathe. Combine that with the current concerns about respiratory infections and you’ll want to attend to your car’s ventilation system.

You can unleash fogger sprays in your closed, unoccupied car while the HVAC runs, or spray them directly into vents. I couldn’t demonstrate one in the video above because I couldn’t find any in stock in time for our shoot date, so high is the run on such products. That’s a nonissue for residents of California, Kansas and Washington states, where the product has been pulled from sale since the top of 2020 due to tightened labelling and application rules. Whatever product you use, the most effective way to sterilize your HVAC and vent system is to find the main air intake, often near the base of the windshield or under the rear edge of the good, and spray the HVAC cleaner in there while the system runs full blast.

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A car air cleaner that contains an ingredient known to reduce bacteria and viruses without the risk to mucous membranes encountered with ozone.

It’s not always labelled, but consider a car vent cleaner that contains triethylene glycol, which has been known to kill bacteria and moderately neutralize some viruses in the air ever since scientific reports looked like this. Unlike ozone, it’s regarded as safe in the air around humans at decontaminating concentrations. 

Note that, as with most products in this list, I’ve found no specific testing of efficacy against the current coronavirus that causes COVID-19. That’s to be expected as the strain is so new.

Cleaning outside air

We’ve cleaned our vents, but what about the air coming in through them? Change your cabin air filter, something you probably never did before. You’ll find standard replacement filters as well as some that are treated with Microban, which claims to at least kill many bacteria. The efficacy of a car’s cabin air filter varies widely with the make, model and year of the car. Our 2004 Crown Vic has a small filter that will barely block insects, while our 2004 Boxster has a large, pleated filter. Meanwhile a Tesla Model S or X has a filter so powerful it claims to block bioweapons and even clean the air around the car.

The role of windows in disinfection 

One last thing to think about is the effect of window tint on germs in your car. Virologists know that UV from the sun is a moderate, persistent virus killer and your car probably sits in it for hours each day. But many of us get tint applied to our windows, a technology that often brags of blocking 99% of UV rays. Guess what you may have just turned off? The sun’s free disinfection service.

Most cars today come with factory-tinted windows, and it’s almost impossible to find out what level of UV rejection they confer. In general, its hard to evaluate the virucidal effectiveness of solar UV on your car, versus the many benefits of having your car tinted. But know that tint may support microbes in your car.

First published March 12.