People who want to train to be an OSHA instructor typically have degrees in health safety or engineering. However, the OTI course is a specialized way to learn about workplace training.
Besides the general training course for instructors, OSHA offers specialized courses for inspectors who want to focus on one area. These courses include nursing-home safety and safety at construction sites.
OSHA's OTI branch offers its training via numerous local institutions, making it possible to take the course in your area. The course takes one full week, but you have the option to take it more slowly, at a rate of one day per week. Some courses are also available online.