Odorless toxic fumes



For the past 5 months, I have been suffering from coughing, headaches, nausea, dizziness, nose/throat/lung irritation and chest tightness due to driving my car. The symptoms linger for a few days when I stop using car but return immediately when driving again. About 3 months ago, I started researching what could be getting me sick. I went to health clinics, car dealers, and mechanics. I have scoured the web to find solutions but only come across posts that mention many complaints with no apparent solutions. I am on a mission to fix my car and my healthy before it kills me.

I have been trying to systematically eliminate all possible sources of toxic fumes. Sadly, I have learned that most things in gas powered cars are highly toxic. After visiting many dealers and countless mechanics I have come to the conclusion that they are not capable nor able to fix a car that has become toxic and would rather you just buy a new car. Unfortunately that might be the only solution for most people.

In my quest to solve this problem I have found the possible sources of toxicity are fuel vapor, refrigerant fumes, coolant fumes, exhaust fumes, mold, interior out-gassing, and oil mist. Most are toxic and carcinogenic even if individuals do not have an allergic reaction when inhaling these substances. Only a few people even notice that all these toxic elements are present in high-mileage vehicles. Even Prop 65 is used to defend the auto industry from blame. Just ask all the dealers.

I tested the vehicle for mold, refrigerant leaks, exhaust leaks, combustible gases, CO and nothing. Interior out-gassing is not really possible in old cars. Everyone wants you to believe it’s something else. I have come very close to determining it is the actual oil in your car such as transmission and motor oil. I have even spoken to many oil service centers and oil companies yet most deny any health concerns.

Remember I said toxic odorless fumes. That already eliminates most gases. As it turns out most if not all high-mileage vehicles leak transmission/engine oil. Just look at any parking lot. Now if oil is leaking so is oil mist/vapor due to the boiling temperatures of the engine. That oil mist builds up in the engine compartment and slowly finds its way into the cabin to fill with toxic fumes. It doesn’t matter if you use AC, recirculate vents, or open all windows. These toxic fumes still enter your lungs when inhaling. Respirator masks don’t even help. There is no odor because the fumes consist of hazardous toxic chemicals present in oil additives. The oil is not actually being burnt. It’s the toxic chemicals that are evaporating.

Ask anyone working with engine oil and few even know about the SAFETY DATA SHEET (SDS). There it clearly lists the hazardous chemicals and additives present in the toxicity report. Some oils are less toxic than others with synthetic oils having the most toxic additives. I have tested by trying different oil types and brands.

Taken from SDS

INHALATION. Oil mist can irritate airways and lungs. Heating can generate vapors that may cause respiratory irritation, nausea and headaches.

So here is the dilemma. If all high-mileage cars leak oil how do you fix all leaks and/or find non-toxic engine oil. The simplest solution which conveniently benefits car manufactures is to get rid of it.

I am 99% sure it is the engine/transmission oil. The clues are everywhere just taking a long time piecing it all together.

Sorry for the length but I had to get this information out to the community. Please send me your feedback and advice to help solve this health concern. Most car dealers, mechanics, oil companies simply don’t care about drivers’ health.


Sounds like a classic case of exhaust fumes getting into the cabin

Possibly exhaust manifold flange gaskets, and the ac is sucking the fumes into the cabin

Exhaust gases displace oxygen, which makes you dizzy

Very dangerous

I suggest you have a shop use their evap/smoke machine to check out the exhaust system

  1. You say it’s odorless. That throws out gasoline, burning/boiling oil, and coolant. The most likely candidate is exhaust gases, but you say it’s been tested, with nothing found. I suppose refrigerant could be the problem, but if it was leaking your AC wouldn’t be working and you’d know it’s leaking.
  2. Mold is reasonable, but again you say it’s been checked. I don’t know much about mold testing, but my guess it may be difficult to completely eliminate as there a wide variety of molds.
  3. Some interiors can off-gas, but that would be more likely in a new car; this has just been occurring in the last five months.
    I’ll suggest two things:
    Double or triple-check the exhaust gas possibility. Carbon monoxide is really dangerous and fits some of the symptoms experienced and the odorless criteria.
    Consider that it may not be the car itself, but something that was placed in the car. I have found all sorts of stuff when I’ve done a car cleaning. If you had it detailed five months ago, maybe a cleaning agent was used for which you are allergic.


Your information about transmission fluid is incorrect. Most of the spots you see in parking lots are engine oil, not transmission fluid. Transmission fluid has a very distinct odor as well as a color - red. When heated, the smell is unmistakable as automatic transmission fluid. I do not think this is your culprit. Hot engine oil also has an odor although not as strong. If your car was producing vapor from either of these oils, it would be detectable and identifiable by any mechanic.

Considering what your mechanics have told you and what the experts here have posted, could you accept that your symptoms might be psychosomatic symptoms caused by the act of driving itself? Does it only happen when driving your own car? Or any car? Have you borrowed a car to test it out? Rented a car? Do the symptoms occur when riding in your car? Riding in ANY car? The answers to those questions can isolate the cause of your condition. Try it and post back, we care.

I wish you luck and good health.


Get a gas monitor with a battery so that you can use it in the car. You are looking for carbon monoxide, carbon dioxide, and oxides of nitrogen. You might find this at a store like Home Depot. Test the air quality before you start the car and check it every ten minutes or so. Pull over and stop the car for the check, of course. If any of thes increase, especially when you get a headache, then exhaust gases are your problem.


I agree.
Most of the fluids in cars are not aromatic; they don’t evaporate into the air. Gasoline does, but that brings with it an odor. Since you cannot detect and odor, it’s safe to concentrate elsewhere.

Carbon monoxide, however, which can cause all of your symptoms, is totally odorless. A good sensitive combustion analyzer should be able to detect carbon monoxide, however it may only be entering the cabin when the car is moving… which means a shop may not be able to verify it while the car is parked. You could try getting a CO detector at the hardware store and see if that registers any CO presence while you’re driving.

The other “toxins” from plastics etc. are typically inert and/or bound with other
However, if you research deeply enough you’ll find warnings about almost any material. Just about everything has an MSDS (Material Safety Data Sheet). It’s easy to get confused.

One question: is this car new to you? If so, that raises the possibility of the previous owner
having been a smoker (I personally cannot ride in a smoker’s car),
having had a scented Christmas tree hanging from the mirror (or some other scented device),
strong cleaning chemicals having been used that are still outgassing.

You can add the above possibilities to the exhaust possibility.


I am having trouble understanding this OP’s problem. I would not put up with a vehicle that made me ill for a month let alone 5. Does this not happen in other vehicles ? Does this vehicle effect anyone else that rides in it. How long does the OP have to be in the vehicle before symptoms appear?


The battery has been overlooked as a potential source of fumes. A bad battery or over charging could produce toxic fumes. I would also try removing any herbicides pesticides or fertilizers from your garage, if applicable, the fumes could be in your garage and accumulate in your car while sitting.


Unless I missed this detail, I don’t believe that the OP told us how old this Acura actually is.
I bring up this point because if it is new–or even a few years old–it is entirely possible that out-gassing from the plastic and vinyl interior parts is the source of the problem.

I know that my current car didn’t stop “out-gassing” until it was ~4 years old, and while the fumes that periodically clouded the windshield never made me sick, I have read of people whose sensitivities/allergies to this type of out-gassing was so severe that they had trouble breathing.

@oamadrigal–What is the model year of your Acura?


Sulfuric acid venting from the battery was also the first thing that came to my mind, but the OP seems to think the offending substance is odorless.

I’m discounting the idea of it being motor oil or transmission fluid. Unless the car in question is in such a state of disrepair that it leaves puddles of oil and clouds of smoke, oil mist or vapor is not really present under normal operating conditions.

Given the odorless component, it almost has to be CO entering the car from a breach in the exhaust system. I assume the OP has installed a quality CO detector in the car?

In all seriousness, I would take three friends for a ride in the car and see what they smell or feel after prolonged driving, and have them describe it.

FWIW, sometimes problems like this just can’t be fixed. I had a customer who complained that some kind of fumes from her car that emanated when she started the car in the morning made her physically ill. Two other shops went over the car in detail as well as I, no one else in her family had an issue with the car, and she didn’t have the trouble with other cars. No solution was ever found so she traded the car.


That seems to be the sensible solution.


For the OP’s benefit, here is an article on the topic of outgassing. While it is about 5 years old, it does provide some good information on the topic:


The battery is not an odorless source of fumes, and it doesn’t make you drowsy

Those are my observations, and I’ve been around a few leaking lead-acid car batteries


I would like to know exactly how these shops determined the exhaust system is in good shape, and is NOT the source of the problem


headaches, nausea, dizziness, can be caused by CO, coughing, throat irritation and tightness in the chest could be caused by exhaust. Like most of the other commenters I am leaning toward CO (engine exhaust) as the culprit here. But CO clears the body in about 8 hours, so symptoms lasting 3 days does not add up.

The OP could get a home CO monitor and use it on it’s battery back in the car. Unfortunately most home units will chirp every minute or so if they are not running on 110 ac. The home units are also not instantaneous read out, there has to be a a continuous amount of CO for a while for them to activate an alarm and they usually do not read below 50 ppm. Perfectly fine for the intended use in a home. But if the OP wants to track this down they need to spend a few hundred $$ for a reliable industrial CO meter.

They could ask a furnace repair company to check for them, they usually have decent CO detectors. Their local fire department usually has a CO monitor, depending on the departments SOP they may or may not be able to do a quick check.

Edit, if the OP has a CO leak in the home furnace or water heater this would explain the symptoms lasting 3 days.


If she is convinced it is motor oil or transmission fluid, she should look for an electric car.
As for the health risks, I drove professionally for 55 years and the health problems I have are likely to the lifestyle of a trucker. Lack of sleep, lack of regular meals and lack of exercise, with some periods of strenuous exercise.


I agree with the others. Everything about the description is consistent with carbon monoxide. The only other odorless thing in a car I can think of is Freon, and the a/c would stop working in short order. I’d have a shop use an exhaust gas sniffer over the entire exhaust system, inch by inch.

Outgassing fumes might be a possibility for an allergy, but the symptoms seem more in line with CO.

Knowing the year of the MDX would really help.


Carbon monoxide will kill you even if it is mixed with pure oxygen. It doesn’t kill you by displacing oxygen, but by binding with the hemoglobin in red blood cells making them unavailable for the transport of oxygen.
CO also turns your blood a bright cherry red color, a fact that coroners use to diagnose CO poisoning.
This property of CO is also used by butchers who impregnate fresh cuts of meat with CO to preserve that red color, but don’t worry about it, it’s not an oral toxin. It only poisons you if you inhale it.
It’s also not a cumulative toxin like lead and mercury, so don’t worry about daily microexposures.


There are new carbon monoxide home detectors with a 10 year battery in them and they do not plug into an outlet, so that chirp every 10 minutes is not an issue. I would get one of these, plus a 10 year ionization type smoke detector and place both of them on the floor of the car for a couple of trips, then install them in your house.

But two things come to mind. First, when you drive the car, is it always on the same route? It could be something along the route instead of something in the vehicle.

Second, it could be mold in the HVAC ducts or more likely, in the bottom of the AC evaporator compartment. If you don’t have a cabin filter, the Honda ducts can trap a lot of organic debris and it collects under the evaporator. It is really difficult to clean out of the older models because it has hidden screws that require the evaporator to be removed.

I had this problem with our 97 Honda Accord and had to cut out the bottom of the box, clean it out and then glue it back together. Not a mechanic friendly design.


Brings up a good question - has the HVAC filter been replaced?