"He says the 'evidence' on passive smoking is based on nothing more substantial than "estimates, guesswork, subjective recollections and even gossip."

And what about the considerable amount of research and carefully-considered opinions of the top scientists and medical experts who have come out in droves to support the fact of the dangers of passive smoking? Does it also qualify, in your strangely-distorted Planet-Zog view of the world, as "estimates, guesswork, subjective recollections and even gossip."