DC2: the easiest way to check carbon monoxide levels is to look at a hemoglobin and check for carboxyhemoglobin levels. This shows how carbon monoxide has bonded to hgb and to what extent. Its not a simple test though because many things raise your carboxy levels .....sadly and most notably we check these levels every 2 hours when someone has attempted suicide via running the car in a garage. 
ABG levels do not directly test for monoxide....they show dioxide only. In order for a blood gas to show effects of monoxide, the person would need to have levels really really high to show the body compensating for that monoxide level. So high that if you aren't in the hospital you are in a precarious situation. An average smoker would be nowhere near these levels at all.
Also....yes, oxygen levels in an ABG can differ between a smoker or a non smoker....but usually not before either significant lung disease has occurred. And that is a big if. If a physician were to diagnose smoker vs nonsmoker purely based on ABG oxygen results, the diagnosis would be wrong ~80% of the time. Respiratory failure is not isolated to smokers. Healthy people end up with decreased O2 levels for various reasons, just as smokers can have normal O2 levels for many reasons.
I hope this helps a little!
ABG levels do not directly test for monoxide....they show dioxide only. In order for a blood gas to show effects of monoxide, the person would need to have levels really really high to show the body compensating for that monoxide level. So high that if you aren't in the hospital you are in a precarious situation. An average smoker would be nowhere near these levels at all.
Also....yes, oxygen levels in an ABG can differ between a smoker or a non smoker....but usually not before either significant lung disease has occurred. And that is a big if. If a physician were to diagnose smoker vs nonsmoker purely based on ABG oxygen results, the diagnosis would be wrong ~80% of the time. Respiratory failure is not isolated to smokers. Healthy people end up with decreased O2 levels for various reasons, just as smokers can have normal O2 levels for many reasons.
I hope this helps a little!