Morning Alves

First it is probably sensible to point out that most users of the Forums are in the UK and rarely have to touch on OSHA requirements.

I don't think those requirements cover scenarios such as the fire and chemical release which you describe but rather which injuries or illnesses might be reportable or recordable.

The relevant standard is 1904 | Occupational Safety and Health Administration (osha.gov)

Now, it is possible that issues such as the fire or chemical release might be reportable/recordable under legislation enforced by an agency other than OSHA.

In terms of the final question, if you are looking at methods of international comparison, possbily the most commonly used is the Global Reporting Initiative standard GRI 403 gri-403-occupational-health-and-safety-2018.pdf (globalreporting.org)

This applies aligned criteria for classifying the severity of injuries and ill health that mostly derive from OSHA definitions. See Disclosures 403-8 and 405-10 at the back of the standard.

Note that as with most other methods of recording GRI 403 will not pick up the vast majority of occupational ill health as the symptoms do not show in whatever relevant time frame.