Health and Safety in Canadian Workplaces for free from the AU Press website. You can also purchase a printed copy of the textbook for $29.95 (versus the $150 you'd pay for a commercial offering).
The book covers all of the usual OHS topics (hazards, legislation, injury prevention, incident investigation) at a university level. It was funded by the Campus Alberta Open Educational Resource (OER) Initiative.
While we'll be incorporating the text into our occupational heath and safety course over the next few months, the OER nature of the book (free digital copies; low cost print copies) means the book should also be a useful resource for workers, employers, unions and not-for-profits.
-- Bob Barnetson