Just bought a 2013 Honda Civic EX & after.

Before you blame it on the exhaust system, try sitting in the car for a while without running the engine. If you still feel sick, blame it on the interior fabric.

I ran into a similar situation about ten years ago with a woman from Stevens Point, WI. Her throat was seriously burned in a house fire, and that made her extremely sensitive to the exhaust coming in through the fresh air vent from the cars in front when she was in traffic, but she found too that it was the interior of her car that she had just bought. After extensive research into her sensitivity, she wrote a book about her findings. Sorry that I don't remember her name or the name of the book.

The exhaust systems of most cars built since the '96 models are so extremely clean that you can suck on the tail pipe and live to tell about it. Basically you'll get bored is all.

Hi 13Civic. Hope you get a reply from EM7. This is about the fourth or fifth case I've heard of but the other cars were years older. All of them were Hondas. It has to be related to the fabric. Seems to me someone figured out it was the headliner, but I don't know that for a fact or what the fix is. In at least one case the dealer bought the car back.

I can only share what I learned from the person I worked with. The comment about nitrogen oxide is not correct. That gas was blamed for acid rain years ago. It is caused by burning fuel at very high temperatures. That is why diesel engines are the biggest contributor. That gas will cause burning eyes and nose. With gas engines, nitrogen oxide is reduced or eliminated by using exhaust gas recirculation, (EGR valve). That puts inert exhaust gas into the cylinders. By partially-filling them with that, there is less room for fresh air and fuel, so less heat is generated.

Starting with '96 models, all cars and light trucks have the "on-board-diagnostics, version 2", (OBD2) emissions system. The exhaust from them is so clean, you can suck on the tail pipe and live to tell about it. If the catalytic converters are working properly, the exhaust is carbon dioxide and water vapor. Typically you'll see water dripping from the tail pipe or the drain hole at the back of the muffler.

There have been anecdotal stories for years about people becoming sick from the special gasoline formulations required in some parts of the country. The politicians create one problem when trying to solve another problem.

I have a hard time believing the exhaust is the cause of the problem because you're breathing the exhaust from the car in front of you, especially when in slow-moving or stop-and-go traffic. The common factor in all of these complaints is the manufacturer. If the cause of the sickness is the gas, the complaints should come from people with all different car brands.

If you suspect fumes are entering the passenger compartment from the engine area, I would entertain a notion to do a miniature version of wind tunnel testing. Part of the OBD2 emissions system includes a means to collect fuel vapors so they don't get released into the atmosphere, and a means to monitor that system. The Engine Computer can detect very small leaks that we would never find with a visual inspection. To address that, the industry came up with "smoke machines". They generate a white, non-toxic smoke that can be injected, then we watch for where it sneaks out. I would be tempted to try to use that to see where the smoke can be made to blow into the passenger compartment. There's only two places I can think of. One is all cars with factory-installed air conditioning have a drip pan for the humidity that condenses out of the cooled air, and a drain tube in front of the firewall to get rid of that water. There's usually a 4"-long rubber hose with a 90 degree bend hanging down, and little air can flow in there.

The second place is the air inlet for the heater system. The only fumes that might come off the engine are from vaporizing oil that has leaked out previously. To prevent those fumes from going into the inlet vent, there's a long rubber weather seal attached to the rear edge of the bottom of the hood. I'd look for that to be missing on a car that was repaired after a crash.

None of my potential suspects should apply to new cars that have never been damaged. My observations are based on logic, and we all know that doesn't always pan out. Hopefully someone will post a better solution.

My original reply goes back to someone I worked with on this before 2008. Her car was a few years old by that time. It seems to me she had the head liner removed and that reduced the effects. That was an unusual case though because due to a fire she was in, she was overly-sensitive to things in her house too.

I remember reading an article about "off-gasing" of some synthetic materials, and it had to do with soft products like fabric upholstery and foam seat cushions. No mention was made of plastic parts. Adhesives would stop giving off fumes once it was fully-cured. That could take a few months, but many of these complaints involved much older cars.

I've never heard of anyone becoming sick from antifreeze fumes. AC refrigerant will vaporize instantly, then sink to the lowest level. If you were to breathe it, the concern would be lack of oxygen, not that the refrigerant is toxic.

The only thing made from asbestos was brake linings, but that went away in the '70s or early '80s. Even then it was not as hazardous as the lawyers on tv would have you believe. Asbestos under a microscope has little barbs or hooks that cause the fibers to attach to your lungs. When it was used for brake linings, and for clutch discs, the fibers that broke free got ground down by the brake drums and rotors and flywheels. Those hooks got ground down too so the fibers could be coughed up. There was no such thing as brake squeal when asbestos was used for brake linings. That problem started when we switched to other materials.

I'm not aware of anything in a car made of fiberglass. Making parts from that is very labor-intensive since parts have to be hand-assembled. Instead, dash pads and door panels can be injection-molded very quickly and to very repeatable tolerances with plastic. You may find fiberglass used for rear spoilers and some exterior trim panels, but it is always finished off with a gel coating. If a part were to break, it could give off fibers, but I've never heard of that being considered hazardous material. The worst thing is it causes itching when it gets on your skin.

Sorry, I don't have any answers other than what I already mentioned. For emissions testing starting with all '96 models, part of the test consists of placing the vehicle in a sealed room, then testing the air after a certain period of time. They're looking for fuel vapor sneaking out of the gas tank, but I seem to recall they were also looking for pollutants from any other sources, to include plastic panels and fabric. Once the EPA is done with that, who is to say the manufacturer doesn't switch to a different adhesive for carpet on doors and other trim panels?

We've also heard horror stories about people becoming sick from the additives in gasoline in some parts of the country. Blame that on the ill-informed politicians. We all know to avoid buying gas in southern Wisconsin. The politicians who demanded different formulations many years ago apparently think the exhaust stays there and doesn't blow over to Michigan