Those links don't actually address the point I was making:

High CO2 levels may be bad, but it's a huge leap to go from there to saying that the air was better when it had cigarette smoke.

For that matter, both of your links say that CO2 levels below 5,000 ppm have no ill health effects other than perhaps drowsiness. And it looks like planes cabins are usually about 1,000-1,500 ppm -- elevated, but again, not clearly worse than having cigarette smoke in the air.