Re: I just want your opinion.
One way to approach this question is to ask yourself how someone else (who you know doesn't have OCD would react). Lets take your asbestos example. Obviously being around asbestos is not a desirable thing and if you are exposed it seems like a reasonable, non-OCD person would take some precautions. Depending on how much exposure they might wash their hands, or take a shower, and maybe even wash their clothes. Where you can start to see the difference between normal healthy concern and OCD level behavior would be considering the proportionality of the response. Were you exposed to a brief bit of asbestos and suddenly felt the need to absolutely decontaminate everything and anything you've been in contact with since? That strikes me as much more of an OCD driven response than what a normal person would do. Are you worrying excessively and unreasonably about possible outcomes? For example with asbestos health problems associated with it are linked to long term exposure, so believing you will die from brief one time exposure would qualify as excessive.
While the outward actions may be different than checking your door ten times for example, the underlying drive is the same: you are trying to erase doubt through seeking re-assurance. You say that if you could eliminate the source of the problem, then the obsessions and compulsions would disappear completely. While that seems logically true, the problem is that for someone with OCD such a thing is not possible. Your OCD driven mind WILL find a way to doubt that the source has been eliminated completely, that's what the obsessions are all about. "What if I didn't wash that cup enough". "What if they missed a spot on the wall". "What if some is still in the air". And thus, driven by your obsessions you will be pushed by the OCD bully inside to engage in your compulsions in a desperate attempt to remove all doubt.
The content of the two concerns (contamination fear and door checking) are different, but the underlying issue is the same: doubt. If you were brain scanning too people with OCD each being confronted with the situation you'd see the same symptoms too. The same areas of the brain would be malfunctioning and overreacting.
The good news from that knowledge is that regardless of the outward presentation of ones OCD, the methods to alleviate it are largely the same. CBT therapy and/or medication can be used largely successfully to address the disease regardless of HOW it exposes itself in a given persons life. Because at the core of OCD is the problem of doubt and how the brain of sufferers just can't seem to handle reasonable proof effectively.