Then ask your friend what the RR is that epidemiologists require to form a casual relationship between factors and results.
Then ask him what percentage of studies on ETS match that RR.
Most epedemiologists require a 2.00 and would prefer a 3.00 before associating any factors with a result.
I'm not trying to demean your friend but there is a lot of difference betwen studies on first hand smoke and ETS.
And I didn't think you would want to see what three of the largest studies done to date actually say, but I thought I'd see how open your mind was.
Studies can cover a wide spectrum for many reasons. I've seen enough solid quality studies implicating second hand smoke, the jury is in, for me.
I have no need to bother my friend as you suggest. He's shown me plenty before. I'd rather he spent his time doing what he does best for the air of Hawaii.