Seven months ago my company turned the clubhouse above my office into an apartment for me.  The clubhouse had not been used for over 8 years.  I began to smell sewer odors shortly after moving in.  Over time the odor became very heavy.  Two weeks ago my maintenance technician checked the sewer stack and the air-conditioning unit and found that two drain lines from the AC had been tapped into the sewer stack.  I have suffered headaches, dizziness, and have become very emotional and lethargic.  I was taken to the hospital five days ago for severe symptoms.  A blood gas test was done and a high (the doctor did not tell me how high) level of carbon monoxide was found.  I was put on oxygen for an hour and told not to go back into my apartment until the problem had been corrected.  What should I do? -Patti, Georgia 

Given that the building has not been used in over 8 years, it is not surprising that you are experiencing a variety of problems.  It is not unusual for sewer gases to enter building air-conditioning units through condensate lines which drain into a sewer system.  This occurs when the air-conditioner is not being used and drain traps dry out.  It is unusual for condensate lines to be connected to sewer gas exhaust stacks.  Such stacks are designed to vent sewer gases upward and outward and not into your air-conditioning unit! 

Sewer gases primarily include methane, ammonia and hydrogen sulfide.  Methane is produced in the highest concentration and is a relatively non-toxic gas.  The symptoms you describe (headaches and dizziness) could only occur if methane were present in such high concentrations that it would displace oxygen causing sub-asphyxiation-type symptoms.  In such an  instance methane levels would pose a potential risk of explosion from even the smallest spark (such as turning on a light switch). 

I doubt that sewer gas is the cause of your symptoms.  High methane levels associated with sewer gas could be expected to result in high ammonia exposures as well.  Ammonia causes severe irritation of the eyes, nose and throat, symptoms you should be experiencing if the sewer gas problem is really severe.

The symptoms you describe are classic symptoms of sub-lethal carbon monoxide poisoning.  Your blood tests appear to confirm that. 

Given the fact that your building was not used for 8 years and your problems associated with sewer gas entry into your apartment, it is not surprising that you may have a carbon monoxide exposure problem as well.  The building appears to have a maintenance problem that may include a gas-fired furnace, water heater or both.  If you do have a gas or propane-fueled furnace, it may have a cracked or perforated heat exchanger.  If this is the case, carbon monoxide will pass directly into your duct system with highest measurable concentrations coming out of your heating registers. 

This can be measured with some of the low-cost digital carbon monoxide testers (e.g. Nighthawk brand) that are available at your local hardware store or discount store. 

If register levels are not higher than the surrounding room, you are likely experiencing a flue-gas spillage problem associated with flue pipes or exhaust chimney.  Check for corrosion and water stains on fluepipes and on the furnace's draft hood.  Such corrosion and staining indicates that flue gases are not being vented properly.  Check this area for CO levels with your digital meter.  Record peak levels over a 24-48 hour period. 

Flue gas spillage may also be associated with a gas water heater.  Check its vent pipe and draft hood for corrosion.

The sewer gas problem is different from the carbon monoxide problem.  They are only associated in the sense that they took place at the same time and  are due to poor or a lack of proper maintenance.