Why are car heaters trying to kill me?

November 30, 2007 10:26 AM

Who do I get nauseous the second the heater is turned on in the car?

I've been going through this for years: in the wintertime, I can tell the heater has been turned on in any car I'm in even before the cabin gets warm. I get a feeling of nausea that intensifies the longer the heater is left on.

I first noticed this years ago, in a cab. I was nauseous to the point of asking the driver to stop to let me throw up, but was able to control myself. Once at my destination, I stepped out of the cab and with one breath of cold, fresh air, I felt instantly better. Now I keep the window near me cracked when I'm in a heated car. Doesn't make me feel completely better, but it helps a little.

Whether it's an adult-onset thing or not is hard to say, because I was born & raised in a warm climate and the heater was never turned on.

Has anyone experienced this? I never feel this way, say, when I turn on the heater at home. It's always in a car - any car.

posted by DrGirlfriend to health (25 comments total)

Could it be carbon monoxide poisoning?
posted by dcjd at 10:31 AM on November 30, 2007

I get the same thing, and have since I was a kid. For me though, it's definitely linked to the temperature itself and not something else about having the heater on, since I get nauseous in the summer when the AC/vent is insufficient in the car.

Sorry, no real answer, just commiserating.
posted by twoporedomain at 10:38 AM on November 30, 2007

I find that I get nauseous if I take too hot of a shower. I'll bet it's the change in temperature (like twoporedomain said). I don't have that problem with car heaters, but then again, I live in a place where it's never used.
posted by parilous at 10:41 AM on November 30, 2007

I have a similar problem. Don't know what it is, but you're not the only one!
posted by misanthropicsarah at 10:42 AM on November 30, 2007

I get something similar, though to a lesser degree - sometimes when the AC is on, too. Cracking the window almost always helps me. I'm not sure what it is, but I always assumed it had something to do with fresh air, or lack thereof, rather than temperature. Perhaps a combination of something funky in heat/AC air combined with motion sickness?
posted by Metroid Baby at 10:54 AM on November 30, 2007

What's weird is that I don't feel that way when the AC is on in the car. My husband does, but the heater doesn't affect him at all.
posted by DrGirlfriend at 11:02 AM on November 30, 2007

I think it's related to motion sickness, the onset of which can be hastened by warmer temps. Worse, one of the symptoms of motion sickness is a feeling of being too warm (while at the same time feeling clammy--never understood how I could feel both at the same time, ugh) and being stuck in an overly warm car just escalates the icky cycle.
posted by jamaro at 11:05 AM on November 30, 2007

I imagine it's carbon monoxide. I am just blueskying this, but if a tailpipe is blocked and people are sleeping in a running car overnight, I believe the carbon monoxide is what subsequently kills them (as well as those committing suicide by this technique). Perhaps there is carbon monoxide in the heat that is causing your reaction.
posted by WCityMike at 11:05 AM on November 30, 2007

I used to get nausea when I was a kid in my dad's car with the heater on. He got his catalytic converter repaired and it went away.
posted by infinitewindow at 11:14 AM on November 30, 2007

Is this particular to a certain car, and that cab? Or does it happen in any car? If it's not in every car, get yours checked for carbon monoxide, for sure.

If it happens in all cars, then probably it's the change in pressure, not the temperature. Differences in pressure between inner and outer ear are affecting your equilibrium, causing a sense of nausea. Opening the window a crack reduces that pressure difference, but probably not completely. Try chewing gum and swallowing frequently. IANAD, but see info on Perilymph Fistula here, you may have a mild case of this. You may know whether you have similar symptoms when flying, going up high speed elevators, or other situations with sudden pressure changes.
posted by beagle at 11:23 AM on November 30, 2007 [1 favorite]

The OP says this happens in all cars and it happens before the temperature in the car even rises. So. It's not a problem with one faulty heater and it's not heat-nausea. And it doesn't sound like plain motion sickness because it just doesn't happen unless the heater is turned on.

So it does sound like there is some chemical at play. I have no idea if carbon monoxide is emitted by heaters. We need a car heater expert here! (Carbon monoxide is *typically* not detected by people, which is why it's so deadly. It simply puts them to sleep. But the poster is clearly atypical, since most of us aren't sickened by car heaters.)
posted by iguanapolitico at 11:23 AM on November 30, 2007

The pressure hypothesis that beagle mentions makes total sense; I just wouldn't have thought that turning the heat on causes a change in pressure. Wouldn't A/C cause such a pressure change, too?
posted by iguanapolitico at 11:24 AM on November 30, 2007

The difference between the heat and AC (other than the temperature obviously) is that the heated air gets that way by passing through the heater core which is a temperature exchanger with the engine coolant. This means that if there are small holes in the heater core you can get bits of coolant (which is just water and antifreeze) aspirated into the air. If you've ever been in a car that smells like pancakes when the heat comes on, that's a sign of a heater core that's on its last legs.

Anyway, so I guess what I'm getting at is there is a plausible path of how contaminants from the engine (specifically, combustion byproducts that seep past the head gasket and dissolve into the coolant) can make it into the passenger compartment through the heater but not through the normal vent/AC system.
posted by Rhomboid at 11:35 AM on November 30, 2007

Actually, I second the motion sickness argument. I generally don't get motion sickness in cars, there are only 2 things that can trigger it, me trying to read, or it being too hot. Something about the heat, and I don't know what, triggers the motion sickness and then the motion sickness spirals it out of control till I get to the point of almost throwing up. This happens even though I am generally a cold person and love having the heat up, it is just the combo of heat + movement that does it to me. You should try sitting in a car that isn't moving anywhere and have someone else turn the heater on and off at points in time (without letting you know that it is on or off at that time) and see what happens.
posted by JonahBlack at 11:53 AM on November 30, 2007

I get nauseous if I'm not driving and it's too warm in a car. I live in Texas, and when I was a kid I would get motion sick (just severe nausea, never throwing up) almost every time I got in a car in the summer. It hasn't been as bad ever since I started driving when I was 16. I think it's because I pay attention more to what's going on outside of the car.
posted by fructose at 12:07 PM on November 30, 2007

People often close the 'outside air' vent when they turn the heat on, so that the cabin heats up more efficiently. Perhaps you are responding to a slight decrease in oxygen:CO2 as the air recirculates, as well as the effects of dry heat on motion sickness. Personally, I'm not very sensitive to heat, but recirculating air makes me sick.
posted by zennie at 12:09 PM on November 30, 2007

Lots of great theories, thanks!

I'm going to try your suggestion, JonahBlack. I'm also one of those who can't read in moving vehicles.

I'm also going to ask a friend of mine who has a new car to take me for a spin with the heater on - I wonder, too, if what Rhomboid mentioned could be an issue. I would imagine in a newer car, there wouldn't be holes in the heater core yet.
posted by DrGirlfriend at 12:57 PM on November 30, 2007

is it possible you've been pavlovianly trained to feel barfy when it's on? maybe it's the sound? you could try desensitizing yourself.
1. drive for a bit.
2. heater on for 2 minutes. think strong, pleasant thoughts.
3. heater off.
4. breathe cool, clean air.
5. drive til barfiness disappears.
6. repeat. add 30 seconds of heater time each time.
posted by twistofrhyme at 1:13 PM on November 30, 2007

For me, it's the temperature on my face that affects me more than anything else. Hot face = carsick. Sticking my face against or out the window on these occasions helps make the sickness bearable.
posted by TomMelee at 1:55 PM on November 30, 2007

i get the exact same thing. in fact, i always thought that everyone, to some degree, feels sick immediately when the heat comes on. only thing that vaguely helps is opening the window, like the poster said. that, and wearing sweaters and coats in the car in winter and never using the heater. ugh. i hate that feeling.
posted by buka at 2:10 PM on November 30, 2007

The same thing happened to my sister and I for ten years straight in my dad's 1987 Buick Park Avenue, and mostly on trips to visit my grandma. Therefore, every time I saw my grandma I wanted to barf.

I never found out what caused it, though.
posted by avocet at 3:47 PM on November 30, 2007

Yes, a sudden temperature rise in the car is a bit nauseating. I have the same (mild) experience when the bright sun suddenly hits my face through the car windows.

In some cases such as dirty taxis (and maybe with particular car heaters) there may also be a slightly off-odor that seems to trigger nausea in a car.
posted by JimN2TAW at 3:49 PM on November 30, 2007

I don't feel nauseous every time the heater comes on, but I feel mildly queasy at least some of the time. I think Rhomboid is right that a few errant stinky molecules are being brought in by the heater. You may be extraordinarily sensitive to some odors, or, perhaps, there's some classical conditioning at work. If you were ever in a heated car while experiencing some motion sickness, or if you felt queasy when you were bundled up too warmly for the car, that experience, even if you didn't get outright ill from it, may have been enough for you to associate the subtle smell of a heated car with the experience of being nauseous. See also: the Sauce Bearnaise syndrome.
posted by maudlin at 5:14 PM on November 30, 2007

I really doubt it's CO since heaters are a heat exchanger with the coolant so there is no path for carbon dioxide that way. However, it is possible that something has been spilt on the heater core and comes into the car when you turn it on. Or it has leaked in the past and you're getting glycol fumes (sweet smell, can make you sick), but that certainly wouldn't apply to every car.

I vote for pressure change; some cars will automatically set the air to recirc if there is a big temperature difference between inside and outside and the heater is on, otherwise the heater couldn't keep up.

I'd also suspect a psychosomatic effect. What happens if someone surreptitiously turns the heater on and you don't know about it? Maybe the one heater in the past was bad (leaky, dirty, whatever) and now when you see a heater turned on, you automatically feel sick.
posted by polyglot at 2:10 AM on December 1, 2007

carbon monoxide, dioxide, whatever. *I* know what I meant!
posted by polyglot at 2:14 AM on December 1, 2007