You know, that’s a really good Q. The Ontario Confined Spaces Reg., Sec. 11(3)(b) says rescuers must be trained in “first aid” and CPR but doesn’t say what KIND OF first aid. Here’s what the MOL guidelines say: https://www.labour.gov.on.ca/english/hs/pubs/confined/cs_15.php

“What level of first aid training and rescue procedure training is required’
The regulation does not define the level of training required. However employers are required to determine the level of training required based on the assessment and the relevant plan and the written on-site rescue procedures.”

This is pretty general and vague. But I guess it means that you’d have to go through each hazard you identify in your hazard assessment and for each one determine:
1. What first aid would be necessary if the hazard occurs’
2. What level of training would be required for a person to provide that first aid’

Just for fun, I checked a sample of 4 other provinces to see what they require. AB, BC and Manitoba were just as vague as Ontario. But Federal OHS Regs. say that at least one of the rescue crew must have “basic first aid” training: Fed OHS Regs. Sec. 11.5(2)(b) One of the persons referred to in paragraph (1)(e) shall be the holder of a basic first aid certificate

Thanks again for the Q and I hope this helps. Glenn