[gabrielthomas]

Originally Posted by Trojan

Wow, excellent thread GTO, thank you for compiling all information and putting it at one place. I had gone through quite a few of these threads when i was planning my 3 state trip.
If at all I need to drive at night, I make sure to keep the window a wee bit open to let the fresh air circulate.
Not doing so I feel is kind of dangerous, especially during winters.

Reason - As we breathe out carbon dioxide, sooner or later the level of oxygen diminishes and since CO2 being odourless is not something which you would come to know of immediately. Lack of good supply of O2 is going to have a direct impact on your ability to react, cause drowsiness, excess fatigue all in all affecting your concentration and danger is usually lurking around the corner.

Can't we use the Fresh Air mode in our Air Cons instead of opening the window?

[EFF-EIGHT-BEE]

Originally Posted by gabrielthomas

Can't we use the Fresh Air mode in our Air Cons instead of opening the window?

Yes you can, but the replenish action would not be as quick as in open window. If you want to use fresh air mode instead of windows, then let fresh air fill in after specific intervals(lets say 20 min) by lowering the windows a bit during a long drive. This is based on my personal experience, I was driving in nigh and despite being on fresh air mode, was feeling sleepy, I lowered the glass a bit and instantly felt refreshness and took a 5 min break after that.

[Trojan]

Originally Posted by gabrielthomas

Can't we use the Fresh Air mode in our Air Cons instead of opening the window?

Hi Gabriel,

Yes, that's always there, but not that effective.

I do most of my trips in the night, so this is my personal experience.

For a comfortable highway cruise, AC needs to be 'ON' as it reduces overall fatigue but the quality of air is not fresh enough and drowsiness sets in.

Opening the windows for a short while livens things up a lot. Try it.


Cheers!
Trojan

[phamilyman]

Help me understand how this open the windows suggestion helps make one more "fresh"? In my experience - one's freshness is determined by how alert / rested one is overall. Any intervention - fresh air or even dabbing one's face with water, makes a marginal and fleeting impact at best.

What have I missed?

In any case, there are tolls every 50-80km, and you need to open your window for a long enough period. That should equalize enough air for the CO2/O2 angle. Keeping the window all during the night only ensures intrusion of all possible smells!

[gabrielthomas]

I'm on a Trip to Alleppey this friday night. i will try it out for sure.

Thanks for the responses BEE and Trojan!!

[anjan_c2007]

Call me old fashioned or conservative ! I never prefer to drive on the highways at night because of obvious reasons.
We tend to doze off in the wee hours of the day after 12.00 am in most cases and that is deadly. And if it is a chauffeur-driven car, we are at the mercy of someone else, who may be or may not be very good in the art.
Many of my friends and acquaintences and their family members have met with fatal or near fatal accidents in the course of night driving, in some cases due to no faulty driving on their part.
As a result, I always try to night halt at the nearest town or city in a hotel, by dusk.Next morning, it is best to start the drive afresh.

[EFF-EIGHT-BEE]

Originally Posted by phamilyman

Help me understand how this open the windows suggestion helps make one more "fresh"? In my experience - one's freshness is determined by how alert / rested one is overall. Any intervention - fresh air or even dabbing one's face with water, makes a marginal and fleeting impact at best.

What have I missed?

In any case, there are tolls every 50-80km, and you need to open your window for a long enough period. That should equalize enough air for the CO2/O2 angle. Keeping the window all during the night only ensures intrusion of all possible smells!

Yes agree with you that after 50-80 km interval fresh air would be replaced by lowering the glass at every toll, but that depends upon numbers of persons in car also. If car is carrying full occupants then the rate of oxygen consumption will be high and one would need shorter intervals to let the fresh air in. Fresh air does helps a lot in refreshing one's mind, with high CO2 levels in the cabin, brain will get less oxygen and one would feel sleepy, this becomes more evident in case of longer drives say >200kms. One will feel more alert in oxygen rich air than stale co2 air this is the whole point. The point raised by you that this will make marginal effect is valid in case of shorter drive or if one has just began his drive after a rest, but these things makes a whole lot of a difference in case of longer drives. Hopes this helps.

[SS-Traveller]

Originally Posted by phamilyman

Help me understand how this open the windows suggestion helps make one more "fresh"?

One tends to set the AC to an optimum temperature for one's comfort - and the more comfortable one is, the more likely one is to doze off. The terminology used to describe dozing off for a few seconds is 'microsleep'.

Opening the windows every few km for a short while changes the comfortable environment inside the car. The smoke, smell, wind, dust, heat, cold, whatever - jolt the driver awake from his comfort zone, and help to prevent microsleep.

A signboard warning about this, commonly seen on Australian highways:

Originally Posted by anjan_c2007

We tend to doze off in the wee hours of the day after 12.00 am in most cases and that is deadly.

Research indicates that the hours of the day when one is most likely to doze off are 1 AM - 4 AM, and 2 PM - 4 PM. For those prone to dozing off, or for inexperienced drivers, it is advised that these two periods be avoided as far as possible, while driving continuously.

Research also indicates that tiredness affects car control as much as alcohol does - most drivers show as much loss of alertness after 17 hours of driving, as someone with 0.05% blood alcohol concentration (the upper limit of alcohol concentration allowed in Australia to drivers holding a full driver's licence).

That said, yours truly does drive overnight, and well over the 17-hour limit fairly often, but then, experience, knowledge of how one's body behaves through prolonged waking, and knowing what to do to prevent microsleep and loss of car control, are things that most drivers are not blessed with. What I do does not have to be emulated by everybody else.

[phamilyman]

Originally Posted by SS-Traveller

One tends to set the AC to an optimum temperature for one's comfort - and the more comfortable one is, the more likely one is to doze off. The terminology used to describe dozing off for a few seconds is 'microsleep'.

Opening the windows every few km for a short while changes the comfortable environment inside the car. The smoke, smell, wind, dust, heat, cold, whatever - jolt the driver awake from his comfort zone, and help to prevent microsleep.

A signboard warning about this, commonly seen on Australian highways:

Agreed - I've been in that zone so I know exactly what you're talking about though I believe microsleep can be caused either by sheer exhaustion or highway hypnosis (driving "in the zone") primarily. But IMHO, there is no replacement for a well-timed break. Personally, I'd rather take a quick 30-60 min nap or even 2-3 hours (as much as required by the body) than distract myself opening/ closing the window every now and then.

Yes, if someone could code this into the ECU/ECM and have the car auto-manage this, then fine - else frankly this seems like too much hassle, and a wastage of precious minutes that should be invested in sleep/rest. It can help alert one at the first jolt of micro sleep but if the sleepiness persists, fresh air doesn't solve it.

IMHO one is far better served by paying close attention to one's symptoms and stopping right away. Just being able to note that one is feeling drowsy and taking immediate action is super critical. Having noted that threshold, opening the windows can make a delta difference - unlike sleep or caffeine. Where stopping isnt feasible, the next best thing that works for me is to load up on caffeine, enough for the next 15-50km to reach safety, whether its a big dhaba or a hotel or a toll naka or a police post, anything. I'm a big fan of pre-emptive / planned naps rather than get into the micro sleep zone where anything can happen.

Having said that, I'll consciously keep the car window slightly open - have an all-night drive coming up for Hampi end of July (if all goes well). Will report back any changes.

Originally Posted by EFF-EIGHT-BEE

Yes agree with you that after 50-80 km interval fresh air would be replaced by lowering the glass at every toll, but that depends upon numbers of persons in car also. If car is carrying full occupants then the rate of oxygen consumption will be high and one would need shorter intervals to let the fresh air in. Fresh air does helps a lot in refreshing one's mind, with high CO2 levels in the cabin, brain will get less oxygen and one would feel sleepy, this becomes more evident in case of longer drives say >200kms. One will feel more alert in oxygen rich air than stale co2 air this is the whole point. The point raised by you that this will make marginal effect is valid in case of shorter drive or if one has just began his drive after a rest, but these things makes a whole lot of a difference in case of longer drives. Hopes this helps.

Did some google. The net is divided.
http://www.americanasafety.com/assoc...f%20Switch.pdf agrees with you.
http://www.sae.org/misc/aaf99/visteon.pdf disagrees vehemently. Drowsiness should be the exact opposite of 300% increase in breathing rate.
Other respected folks agree with the theory and present even more scary data: http://www.engr.ucr.edu/~heejung/pub...13-CO2-exp.pdf


Other field tests reveal high CO2 buildup happens very quickly:
http://papers.sae.org/2008-01-0829/

cabin concentration levels reaches ASHRAE (Standard 62-1999 / 700ppm) specified magnitudes in first 5 minutes of driving with only one occupant in the vehicle. Hence, operation of the vehicle beyond 5 minutes will result in much higher levels of cabin carbon dioxide concentration then specified by ASHRAE standard. This situation would be much more severe if a number of people are sitting inside the vehicle and are going on a long drive.

http://ec.europa.eu/enterprise/secto...n/bosch_en.pdf Agrees with the above.

Surprised that our car mfrs haven't come with an auto-outside-air control mechanism for our cars yet. It is an idea whose time has come!

[bblost]

If you keep the window slightly open, then you will have wind noise. That will cause fatigue.

[phamilyman]

Originally Posted by bblost

If you keep the window slightly open, then you will have wind noise. That will cause fatigue.

EXACTLY. I didn't mention that lest others rain down upon me. I find it really annoying.

[SS-Traveller]

Originally Posted by bblost

If you keep the window slightly open, then you will have wind noise. That will cause fatigue.

Originally Posted by phamilyman

EXACTLY. I didn't mention that lest others rain down upon me. I find it really annoying.

A bit of sudden noise on rolling down a window for a short while helps to make one more alert. It's not about continuously keeping a window open by an inch, but doing it at regular intervals and winding it back up.

The rumble strips/cat's eyes along the lane markers on highways also perform the same function. A sudden bump-thump noise from the suspension makes one alert to the fact that one is unknowingly deviating from one's lane.

Another couple of pics from Australian highways:

[phamilyman]

I have a question on CO2 poisoning. Anyone whose stayed in Delhi (or any large city) would have been witness to those crazy days when you spend 2-4 hours driving across the city but are stuck in traffic - e.g just after a heavy rains or during the peak marriage season.

At that time, one has 2-3 folks in the car, the AC is running, and windows may not be opened for easily 2-3 hours as well. But no one suffers any side effects. Then why is sleeping inside the car with windows shut such a big deal? What changes?

[SS-Traveller]

Originally Posted by phamilyman

I have a question on CO2 poisoning.
What changes?

It's not CO2 (carbon dioxide) but CO (carbon monoxide) that poisons and kills.

New generation engines do not emit CO as much as the older carburetted engines did, in the days when this advisory was put out.

I'm afraid we are completely off-topic here with relation to the topic of the thread.

[phamilyman]

Originally Posted by SS-Traveller

It's not CO2 (carbon dioxide) but CO (carbon monoxide) that poisons and kills.

New generation engines do not emit CO as much as the older carburetted engines did, in the days when this advisory was put out.

I'm afraid we are completely off-topic here with relation to the topic of the thread.

Actually it is totally relevant - the past couple of pages talk about CO2 build up while running the AC on recirculation leading to drowsiness which is not good for night driving. I wasn't asking about CO poisoning - maybe the word poisoning was an incorrect choice.

Ideally the CO2 buildup inside cabin leading to drowsiness and other side effects theory (look at the CO2 concentration charts) should apply to regular driving inside city as well as I mentioned, esp on the really crazy days. Heck in the city, if its a bad rainy day, you won't step out of the car, nor even roll down the window for paying toll (as one does on a regular highway drive).

If it doesn't affect anyone when stuck in 3-4 hour long drives within the city when the windows aren't being rolled down at all, I'm a bit skeptical about worrying about it when driving through the night.

Maybe manufacturers' spec already include a small % of recirculation of outside air? This seems like such an obvious issue for most manufacturers to solve, no?