I'm not trying to be difficult when I ask the following question; I'm quite serious. What you're describing sounds quite time consuming and expensive. How much time and money are spent in Canada, for instance, going around interviewing the friends, families and co-workers of all the many thousands of non-smokers who die each year in order to determine what type of exposure they had to all the environmental factors that can contribute to lung cancer? After all, a person's medical records don't tell whether he had a smoking spouse or co-worker, or whether and how often he frequented establishments where he might have been exposed to SHS, or whether he played poker every Friday night in a smoked-filled room, or whether he spent a lot of time cleaning his pool with chlorine, etc. Someone has to do a lot of leg work to find out this kind of information.
You are 100%. That's why we have the CDC, EPA, AMA and the tons of other gov't agencies to do this. Also, the insurance agencies have huge mortality tables (spelling?) that deal with this. If you smoke, but your wife does not; your bill will reflect a smoking household, as the insurance's future stability depends on predicting the statistical odds of future claims.