Is Recirculating Interior Air Dangerous?

I have a 2002 Camry XLE V6 with the automatic climate control system. Can anyone comment on the dangers of driving extended periods (several
hours) with the automatic climate control system set to "auto" and the air source set to re-circulate? By default, the automatic climate control system sets the air source to external (fresh) air. I normally drive in this mode. However, I sometimes set the air source to re-circulate when driving through tunnels or through dusty work zones. On several occasions I have forgotten to set the air source back to fresh air once past the hazard, and continued to drive for several hours with the air source set to re-circulate. I'm concerned about the possible health issues of doing this.
The owner's manual does not have any explicit warnings about driving in this mode, but is it possible for carbon dioxide (from my respiration) to reach toxic levels? I recognize that carbon monoxide from the exhaust system is another potential danger, but my car is well maintained, so perhaps this risk is minimal as long as the car is moving?
When in re-circulate mode, does the Camry's ventilation system allow any fresh air to enter? If not, how much air enters the car via other sources? Searching the web provided the following information, but I don't know how it applies to my Camry since it is quieter (better air seals) than many other cars.
From http://ehp.niehs.nih.gov/docs/2001/109-9/focus.html … however, air exchange introduces the further potential for exposure to contaminants from outside the vehicle. Even with the windows and vents closed, air circulation rates in vehicles are typically high, especially at high speeds. For instance, in the 1997 California study, the air exchange rate in a 1997 Ford Explorer standing still with the vents on the "recirculate" setting and the fan on "low" was 1.8 air changes per hour, more than in the average home. When driven at 55 mph with the vents and fan on the same settings, the rate inside the car increased to 13.5 air changes per hour. The 1991 Chevrolet Caprice, driven at 55 mph and with similar vent and fan settings, had nearly triple the Explorer's airflow, with 39 air changes per hour.
Thank you, --David
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David wrote:

In a California study a few years ago, they found keeping the windows up, fan on high and A/C in re-circulate mode results in slightly cleaner air inside the car.
It is very safe to drive like that. I have done it hundreds of times. It has never killed anyone.
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c0smic wrote:

That's a load of crap.
Apparently the world "cleaner" needs clarification.
If you've got four breathing animals in a small confined space, the air does NOT become "cleaner."
--

- Philip @ Maximum Torque RPM





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Philip® wrote:

Phoooeeeey! ROFL
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There is no danger. Even in the recirculation mode, the intake admits plenty of nice fresh outside air.

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David wrote:

It does? Apparently you haven't had an air plenum chamber apart. The air flow control door has sealing strips and in the case of Toyota, seals pretty well against fresh air being mixed when the Recirc bottom is selected.
--

- Philip @ Maximum Torque RPM



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On Mon, 14 Jun 2004 04:33:36 +0000, Philip® wrote:

Open the driver side door, turn on recirc, turn the fan full blowing power, now shut the door sealing the cabin while listening to the fans.. They do load up even in recirc mode as they build pressure in the cabin with a little outside air. There is air that does get in, not near as much as if you turn off recirc mode, the fans really load up then and wind down a bit as they are now pressurising the cabin more with outside air.
DRACO-
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DRACO- wrote:

Sorry ... that doesn't wash. Cars have for years ... had a one or more rubber one way flapper vents into and out of the trunk. Toyota is no exception. The car's cabin air may pressurize ever so slightly with the fan ON/Fresh and/or by driving at speed with the fan OFF and the air flow door set for FRESH. There is no way for the cabin to pressurize in RECIRC mode ... unless you are drawing air in from the outside.
--

- Philip @ Maximum Torque RPM



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When my wife drove our Camry 300 miles with herself and four kids with air on recirculating, I thought it was pretty unhealthy. All inside windows were covered with steam, telling me that they had been breathing air also recirculated by everyones lungs for 5 hours. The Camry is really tight; even half way on the fresh air makes a big dif.
Also, we got this car when it was 2 years old. It had only been driven on recirc, and it smelled like it as mold/fungus were starting to colonize the air handling system. Keeping the air on full fresh fixed this, but it about a month.
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On Fri, 25 Jun 2004 04:47:59 +0000, Philip® wrote:

*pokes Isnt that what I said? Even in recirc mode it brings in some air.
DRACO-
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DRACO- wrote:

In RECIRC, outside air is not allowed in unless ... the air flow control door seals are rotten. Maybe you wish to rephrase you post? ;-)
--

- Philip @ Maximum Torque RPM



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Depends on how many beans you ate for lunch.

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None.
The reason that it goes to "external" is because "recirculate" should be used only when the AC compressor is running. If the AC compressor is not running, humidity could build to the point that it creates a fogging hazard. In auto mode, the car will cycle the compressor off and on to maintain the desired temperature.
If you can see through the glass, there is no health risk. If you can't see through the glass, there is a health risk, but not in the way you were thinking :)
Recirc is actually the most efficient way of keeping the vehicle cool.
--- Rich http://richlockyer.tripod.com /
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The comparison to houses is a joke because houses have 100 X the sq footage
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Rich Lockyer wrote:

Staying in Recirc mode most of the time is also the way you promote mold growth on the evaporator.
--

- Philip @ Maximum Torque RPM



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Yeah, but it helps your cabin filter last longer. :-)

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Mark Pippin wrote:

That would be appropriate from someone who revels in their own flatulence ;-) . Fact of the matter is you can blow out that air filter a time or two.
--

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David wrote:

The fact of the matter is that no car, even if it's a Bentley, is completely airtight.
There will always be outside air getting in, so this asphyxiation that everyone keeps talking about won't happen. I dare ya to try it...
Jason
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I agree with Jason. I have a 97 camry V6 and use recirculate about 80% of the time. There is no problem. If you are driving behind a diesel with your recirculate on, you can still smell the diesel coming into the car but it is reduced. Also think about it, would Toyota leave themselves open to litigation for suffocating camry drivers? ;)
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Hi,
all cars are vented so you won't suffocate sitting there without the engine on or car not moving. There is always some fresh air getting in - just nowhere near the amount you would normally get sucking it in through the front vents.
Recirc mode is only recommended for quick cooling or driving in dusty conditions - or other environmental hazards like smelly diesal in front or leaking LPG tanks.
You won't kill anyone, unlikely to get sick etc but its not recommended for extended periods - if only for the fact that the equipment is not designed to handle it - condensation build up and foggy windows.
Like anything, its better to have fresh air than recirc air - unless you live in Taiwan where the fresh air has a distict rotten egg smell to it...
rgds
Peter

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