Clean Your Car for Mold to Prevent Cross Contamination and Ongoing Mold Sickness

By Catherine Fruechtenicht

Indoor air quality is a concern not only in our homes, but also in our cars. If you have been sensitized to mold, you don’t have to spend much time in a mold-contaminated car to start to have symptoms and to feel pretty awful again. As a matter of fact, I get emails everyday from mold sufferers who were able to get out of or to successfully remediate moldy homes, but who are still quite sick, because of continued mold exposures in their automobiles. This is a common problem, and you can probably see why: if you are living or working in a moldy indoor environment, and are then using your car on a daily basis, you are bringing mold and mycotoxin hitchhikers with you into your car each and every time. When describing how mold hitchhikes, I actually think Dr. Dennis said it best:

“I have never had a mold patient whose clothing and personal belongings, when TAP tested in my office, did not show high levels of mold spores. Mold spores can be found anywhere there is moisture. They hitchhike on your clothes, on your pets, even on packages.”

In other words, if a patient was sick from mold in their home, they inevitably also had high levels of mold spores on their clothing and things. Those spores were hitchhiking from the moldy home and were going with the patient wherever they went. And, how did those patients get to Dr. Dennis’s office, or to anywhere else? That’s right, 9 times out of 10, a car.

Your Automobile’s Ecosystem

Like a house, a car has its own ecosystem. It has carpet, leather, and plastic surfaces, a combustion system, and a heating and air conditioning system. It has the human and biological components of sweat, breath, germs, bacteria, and fungi that it is exposed to. It also communicates with the outdoor air and environment each time a window or a door is opened. In addition, if we close the windows and run the heating or air conditioning, a car can be as much of an envelope as any indoor environment. Thus, our cars, like our houses, can get moldy.

(Note: A 2011 study published in the Journal of Occupational Medicine and Toxicology found that exposure to bacterial endotoxin and fungal β-(1,3)-glucan may also occur in the car indoor environment and can induce major respiratory symptoms. Scientists sampled dust from the passenger seats of 40 cars. Endotoxin and β-(1,3)-glucan were detected in all samples. It was concluded that endotoxin and β-(1,3)-glucan exposure in automobiles at levels found in this study may be of importance for asthmatics.)

Mold Sources in Cars

Cars can harbor mold for many reasons. Here are some of the most common culprits:

  1. Excess Moisture, Leaks and Water Intrusion

Sometimes, a water source is introduced that is not aired out or dried properly and mold grows on the porous materials in the car as a result. Remember that a water source in a car is not necessarily the same as a water source in a home. You can get leaks or outside water coming in, but many times, water is introduced from something that is seemingly innocuous, like wet shoes, a spilled water bottle, moisture from melting frozen goods in grocery bags, damp towels from a day at the pool or beach, a wet umbrella. All of these things may seem like only small amounts of water, but if not dried out or wiped up, each can create big mold problems down the road. An example of a water source creating problematic mold growth in a car is from a man who wrote to me about his favorite sports car. The car had started to smell musty and to cause him to have severe allergy symptoms whenever he drove it. I guided him to take an air sample with some test plates inside the car and to also use some plates to TAP test various places in the car for mold. Test results showed high spore counts both in the air near the dash and the TAP test of the carpet beneath the dash. It turns out that the carpet in that area had been saturated from a spilled bottle of water some time ago. Because he had not taken measures to thoroughly dry the carpet, mold had taken hold. Every time he used the heat or air conditioning, mold spores were being dislodged and blown about by the airflow. He was able to fix the problem by shampooing and treating the carpet with EC3 Mold Solution Concentrate, then using a shop vac and fans to extract and dry everything out. He then flushed the heating and air conditioning system and changed his cabin filter. Afterwards, his air and TAP tests were perfectly clear and his symptoms subsided.

  1. Faulty auto air conditioners

This is a hidden water source, because it can occur as a slow leak or as a draining issue, where water pools in the system and causes mold and bacterial growth. It’s a malfunction of the air conditioner that continues for the life of the car. Apparently, with some makes and models, this is a common problem. So common, in fact, that some manufacturers have issued advisories and at least one law firm is advising automobile owners with mold problems to use the Lemon Law in their state to try to get the manufacturer to buy the cars back. The best way to avoid this issue is to thoroughly research and read through car forums for the make and model you have or are looking to purchase. If you find many AC complaints and complaints about mold issues, stay away from that make and model of vehicle or contact the manufacturer directly to complain if you are having similar issues. If it is a fault in the air conditioning system, it will continue to occur and the mold will continue to grow no matter how you clean, treat, or remediate the car. In these cases, it is best to get rid of it, so that you can get well.

  1. Moldy materials or microbial growth on or around the air conditioner’s cooling coil

Just like in a contaminated HVAC coil in a home or building, a contaminated coil in a car can cause severe mold issues and sickness. If your car has a suspicious sweaty sock odor from bacteria or yeast, or the earthy odor of mold, consider taking it to an automotive technician to remove the entire air conditioning system and clean it, or you can try treating it yourself with a less aggressive method I will outline later at the end of this article. Also, if there are fibrous insulation materials near the coil, have them replaced, if possible, with a non-fibrous insulation such as closed-cell foam. (Note: If automotive heating and cooling systems had filters that were at least 40% efficient at filtering fine particulates from the air, they would reduce the number of potential nutrients that can enter the system and influence the level of biological growth. Unfortunately, as far a as I know, not many auto manufacturers have heating and air conditioning systems with filtration. Most cars do have cabin filtration, but that does not directly influence the coil as much.)

  1. Parking Your Car in A Moldy or Contaminated Enclosed Space

If you park inside an enclosed, moldy space, your car is inevitably going to become contaminated as well. Anytime a door is opened, or a window is left open, the mold spores from the garage enter and settle into the car. I received an email from a young medical student who was suddenly feeling terrible every time she drove her car. She had just returned home to stay with her parents in Florida before starting her residency. Her fatigue and brain fog were starting to really worry her. She sent me some pictures of the inside of her car to see if I could see any mold issues. What I saw in one of the pictures was not mold in the car, but black mold all down the side of a boat that was parked in her parents’ garage right next to her car. Each day she had been home, she had pulled into the garage and parked alongside the boat, and left her car windows and sunroof open, because the garage was totally enclosed. When I asked her if she had noticed the mold on the boat, she definitely had an AHA moment. She began parking outside, thoroughly cleaned and remediated the car and AC system for mold, and was on her way to feeling much better.

  1. Mold Cross Contamination from a “Sick” Home or Building

Cross contamination, like I said at the beginning of this article, is very real and your car can become a huge source of mold spores and mycotoxins because of it. Mold hitchhikes from the moldy environment on your clothing, skin, hair, purse, shoes, etc. and enters your car. The more you go back and forth, and expose your car, the more intrenched the problem can become. Thus, it is extremely important to always protect your car and to practice regular mold maintenance in it just as you do in your home. This will help to keep mold counts down in the car and will help you to get and stay well.

Another common mold cross-contamination issue is when mold spreads under the padding and material in the trunk if and when you transport moldy contaminated items from your moldy home with your car. If contaminated items are transported without being completely sealed in plastic bins or properly remediated first, the entire vehicle can be exposed to the mold. Also, most newer cars are not sealed between the trunk and the back seat. Thus, the contamination is not contained to just the trunk.

How Do I Prevent Mold in my Car?

The first step with mold is always prevention, if possible. It is a lot easier to maintain a healthy car environment than it is to remediate one that has become “sick,” because of mold. Here are some easy steps to help you practice good mold hygiene in your car:

  • Once a week, shake out your floor mats, vacuum your interiors, and wipe down your seats and console with EC3 Mold Spray.
  • Place clean plastic bins in your trunk or in the back of your car, so that you can place wet shoes, towels, umbrellas, grocery bags, etc. directly into the bins, rather than onto upholstery or carpeting that may soak up the moisture and grow mold. When you get home, remove the wet items (never leave anything wet in your car for a prolonged amount of time), and dry out the bins completely.
  • If possible, replace upholstered or carpet floor mats with rubber mats. Some chemically sensitive people cannot tolerate this, but if you can, these mats are much easier to clean and to wipe down, and do not absorb excess water.
  • Change your car’s cabin filter every 4 months. You can do this yourself by reading your car’s owner’s manual, or you can have any auto service technician replace it for you. There are also many videos on YouTube that show how to do this. I like Cleenaire Automotive Filters, because they have multiple stages of filtration and utilize coconut charcoal which is less reactive for most people.
  • Flush your vents with EC3 to prevent mold growth every 4 months.

    Each time you replace your cabin filter, once the old one is removed, use EC3 Mold Solution Concentrate diluted per package instructions to spray into the outside windshield wiper vent where outside air is being sucked into the cabin when the defroster is on. Clean all debris away from the outside air vents. Start the engine and put the AC on the defrost setting. Spray the EC3 in the vents, about 40 sprays per side. Allow the car to run for about 10 minutes to let the solution circulate through. You can also use 1 cup EC3 Laundry Additive in 1 quart of water in a spray bottle for this same application. Replace the cabin filter with a new one when you are done.

  • Make sure windows, sunroofs, doors, and trunks close and seal properly. If you notice any water intrusion, have it repaired ASAP.
  • If water gets into the car for any reason, remove floor mats and use fans and dryers to remove all moisture ASAP. Mold only needs 24 hours to take hold, so time is of the essence.
  • If you notice any off-putting or musty smells, use EC3 Test Plates to find out the source and whether or not it is mold. Doing so proactively will help to solve the problem and to prevent sickness.
  • Do not park your car in musty, visibly moldy, or water-damaged garages. It is better to park outside than to potentially risk cross contamination and exposure.
  • Do not transport moldy or contaminated items in your car. If you have to do so, use plastic bins that seal completely to store the items in. Then, once the items are removed, thoroughly spray down and wipe the bins with EC3 prior to putting them back in your car.
  • Consider using an air purifier in your car for extra protection and filtration. The Atem by IQ Air is my favorite, but it is pricier. There are many options, but make sure it does not emit ozone.

Can I Perform Effective Mold Remediation on My Car?

(Note: If there is visible mold growth or your car has been severely water-damaged by flooding or storms, I do not advise attempting to clean it. In these situations, the risk is not worth the reward. Your health and well-being are more important than trying to salvage the car.)

If your car has been exposed to mold and mycotoxins, smells musty, or you suspect mold in your car is making you sick, you can try some of the following techniques to clean it. My number one caution is that no one method works for everyone. If you clean your car for mold and continue to feel bad when you drive it, or it continues to smell musty, it is best to try to sell it or to trade it in, rather than risk your health. Also, if it has the faulty air conditioning issue I discussed above, it cannot be fixed with cleaning alone.

How to Clean Your Car for Mold

  1. If there is a source of water intrusion, it must be fixed first. No amount of cleaning can keep mold at bay if water continues to enter the car.
  2. In cases where floor mats are the definite source of the mold growth, it is best to discard and replace them.
  3. Remove all floor mats and loose materials from the car.
  4. Thoroughly vacuum the entire interior of the car, including the console and the area underneath the spare tire. Anywhere there is surface area, you need to vacuum. Shop Vacs with replaceable HEPA filters are great tools for this. They are powerful and easy to move around your vehicle.
  5. Use Dawn dish soap and hot water to thoroughly scrub and rinse clean the floor mats. I like Dawn, because it is a powerful surfectant and cuts through grease and oily residue. If you have a power washer, use it. It will help to extract dirt and debris. When you complete washing them, they should be placed in the sunshine, or in front of high-powered fans to dry. They must be dried completely. Once dry, spray with EC3 Spray and vacuum thoroughly again before placing back in the car.
  6. For leather seats, console, doors, and all plastic surfaces, spray and wipe down completely with EC3 Spray.
  7. For upholstered areas and upholstered seats, it is best to take the car to an experienced detailer to shampoo and steam clean. Have them use Dawn and the EC3 to treat the upholstery. Advanced drying techniques and fans must be utilized to dry the interior completely. If you are going to do this yourself, I would not shampoo. I would spray everything down with EC3, then use a steamer to steam all seats and upholstery. Then, I would treat it with the EC3 again and allow it to dry.
  8. Remove the cabin filter. See the steps outlined above for running EC3 through the ventilation system. Replace the cabin filter with a clean, new one.
  9. Consider having the entire AC system flushed, cleaned, and/or the coil cleaned or replaced, if you suspect a mold on the coil.
  10. Use mold test plates to test the air and materials inside your car to make sure it is testing at safe mold levels once all cleaning is done.
  11. Utilize the mold maintenance techniques outlined above to keep mold levels down.

I hope you found this information helpful. I also hope you will consider checking out my blog There I post articles about my personal mold journey, cleaning for mold, interviews with doctors and professionals who help mold patients, and environmental illness treatments and recovery information. Feel free to comment below with questions or to write to me anytime at