This is true but it is only a short term example. If you have enough CO2 in your blood to make it just slightly more acid than normal, your immune system slows down, allowing cancer to grow over time. Cigarette smokers have more CO2 in their blood than others hence the greater risk of cancer.
Wrong. If this was true people who exercised would be more prone to cancer because any activity would, under your explanation, make them acidic and victims of cancer. We know that the opposite is true. People that exercise are LESS prone to develop cancer. The explanation PZ puts forth does not hold true.
Cigarette smokers are more prone to cancer because of the nearly 6000 chemicals found in cigarette smoke, many well known carcinogens like Benzene.
I wonder if anyone else has had the impression that you like to be contradictive. It is best that we include documentation with our claims otherwise we are engaged in endless circles of discussion.
Your claim struck me as not making sense. I think that people who exercise properly have better oxygen absorption capacities than those who don't. Also exercise helps rid the body of toxins.