What about the Spanish speakers? Find someone to speak in Spanish. Don’t rely on Google translate — you need to find someone who speaks the way they speak on the job (remember: personal).
You can control the timeliness and effectiveness of your safety message with assets you already own (jobsite photos) and send them to workers when they need them.
Being a safety salesperson, you cannot afford to be associated with the Death of a Salesman... or the Death of a Laborer.