Tuesday, April 4, 2017

All about Carbon dioxide

Carbon dioxide?  Is that the dangerous one? 

You might be talking about CO, or carbon monoxide.  That’s the stuff that can kill you. Carbon dioxide is CO2.

So carbon monoxide is the one they are talking about when they say “carbon pollution.”  Right?  

No.  Pretty sure they are talking about carbon dioxide.

So carbon dioxide is really the dangerous one?

Well, not sure I can explain how carbon dioxide, which is absolutely necessary for all life on earth, became a pollutant, but that’s the story.  It’s referred to as a “green house gas” so it apparently contributes to global warming. 

So carbon dioxide is the most plentiful of the green house gases?

No, not really.  I believe water vapor tops that category. 

Why all the concentration on carbon dioxide then?

Not sure.  But I think water vapor would be very difficult to regulate.


Carbon dioxide is much of what we and animals exhale.  It is necessary for all plants as part of the process for photosynthesis and produces oxygen, which we obviously need.

In terms of indoor air quality (IAQ), levels of CO2 generally do not reach dangerous levels, but this does not mean there is no effect.  If you notice workers getting drowsy in the afternoon, it might be partly an effect of needing a nap after lunch.  Another possibility is that CO2 levels have built up due respiration and insufficient outside air to dilute.  Fresh air is needed! 

To a large degree, CO2 is used as an indicator gas to determine if there is sufficient outside air being provided to an area of concern to dilute normally present contaminants.

In an office, if illnesses tend to be passed quickly around the office, don’t be surprised if carbon dioxide levels are high.  This indicates insufficient outside air to dilute the contaminants, including germs causing illness.   Thus occupants are exposed to higher levels of the cause of the illness and are more likely to succumb to the illness.

There are many other potential contaminants that are present in normal office or residential environments.  Such items as volatile organic compounds (VOC) that can be generated by paints, coatings, cleaning materials, etc.,  or formaldehyde that is often present in particle board furniture will continue to off-gas for long periods of time and will build up if not diluted.  Levels can be reached that can cause health effects to some if not all occupants.

Here is an example with which most people are familiar.  You have a room in your house that is mainly used for storage.  You have the door closed and no window open.  After a couple of weeks you enter the room and are hit by a strong or stale or musty odor.  Open a window and leave the door open for awhile and the odor will eventually go away.  This means the contaminants have been diluted by outside air.  But in more subtle situations, it is CO2 that signals the build-up.

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