Smoking and Carbon Monoxide

Factual Questions
1

Smoking increases susceptibility to anaemic hypoxia, i.e. inability of the blood to carry oxygen, partly because it increases the amount of carbon monoxide in the blood. I know it has other effects, but this post is only concerned with the effects of carbon monoxide.

This effect is of significance to pilots as the inability of blood to carry oxygen, combined with lower air pressure at altitude induces hypoxia - for smokers this occurs at a lower altitude than non-smokers.

Two questions;

  1. Is the reason carbon monoxide reduces the blood ability to carry oxygen due to the carbon monoxide bonding to the available oxygen in the blood to form carbon dioxide?

  2. Presumably the carbon monoxide is eventually flushed and eventually eliminated from the blood. How long after smoking a cigarette will the carbon monoxide still be present in the blood to have a noticable effect?

2

It takes 8 hours for the carbon monoxide level in your blood to reduce by 50%. 24 hours and it will be eliminated completely. From the NHS stop smoking website.

3

I believe the carbon monoxide binds to the haemoglobin in your blood, the haemoglobin usually bind to oxygen (becoming oxyhaemoglobin) to carry it around your blood however, they bond to carbon monoxide more strongly so it results in your body having less cells in the blood able to carry oxygen and so less oxygen going around your body.

4

You are correct, but just to clarify I’ll note a few things:

  1. Oxygen needs to be carried by hemoglobin in your blood.

  2. Carbon monoxide is carried over 200-times better by hemoglobin than is oxygen.

  3. Once carbon monoxide is being carried by hemoglobin, it stays there for a long time (unlike oxygen which is rapidly released by the hemoglobin)

This means that if you inhale carbon monoxide there will be fewer empty spots on your hemoglobin left to carry oxygen, and it will stay that way for a long time - even after you’ve stopped inhaling the carbon monoxide. You will suffer from lack of oxygen, not because there’s not enough oxygen around, but because there’s no room on your hemoglobin to carry it to your tissues.