I know essentially nothing about this topic, but it seems likely that some particles are more dangerous than others (though I've seen no suggestion of that). I'd prefer to go after the elephants in the room before the hamsters.

There are MULTITUDES of particles in circulation everywhere everyday. If the impact of only some these are especially dire, we should be able to triage each particle simply by: 1) looking at who suffers most from 'lung cancer of unknown etiology' and what environmental particles they were exposed to, and to a lesser extent, 2) looking at who is exposed to each type of particle and whether they suffer from it.

It'd be nice if we had some clear hypotheses in mind before charging off in all directions.