Ford F450 super duty regeneration cycle

I work for a company that has around 200 f-450 2008-2010 super duty trucks.
I'd say approximately 60% of these trucks have fumes that leak into the cab
when the regen is on. The trucks rarely leave the city or are on highways so they
are constantly running in regen mode. Usually 80-100% of the shift its in
passive or active regn. Our shifts are generally 10-13hrs of driving. After a few
hours of breathing in the fumes I notice my eyes start to sting, throat gets sore,
headache begins and I get very tired. When I bring this up to our management
and mechanics everyone assures me the regen is completely safe, I can't help
but notice none of these symptoms occur in the trucks that don't have regen
fumes that leak in the cab. Are my symptoms completely a coincidence? How
often do these filters need to be changed or cleaned out? (Majority have
300+km on them) Are regen fumes toxic? Is there a way to stop a regen cycle?