"Further, these conditions can be multi-causal in origin. Consequently, individuals exposed to ETS may not associate a respiratory condition they experience with their workplace exposure. If the association is made, the individual may not be aware that s/he can claim for this type of exposure."

Non-sequitur. Even assuming that ETS causes the diseases attributed to it, if a disease is multi-factorial (like the large majority of disease is), it is impossible to establish the amount of contribution a particular factor, or even if that factor is contributing at all - expecially when the risks are statistically insignificant.

The blatant contradiction expressed here demonstrates that it is wasteful to try to isolate one factor among many that are interacting in a virtually infinite number of ways. It also show the political rather than scientific motivations of smoking bans.