[TimT]

respirators can't filter them out.

Not true.

Properly fitted half face or full face masks, with cartridges that are changed before its useful life is exceeded are acceptable.

This means for most hobby, home painters, new cartridges every time you spray.

A supplied filtered fresh air supply is recommended

https://www.grainger.com/know-how/health/airborne-contaminants-noise-hazards/respiratory-protection/kh-233-isocyanate-qt

https://www.grainger.com/know-how/health/airborne-contaminants-noise-hazards/respiratory-protection/kh-respirator-cartridge-change-schedule-196-qt?cm_sp=CM-Shop-_-inline-text-_-kh-233-isocyanate-qt-_-2020-05