The history of fire resistant clothing predates the photo by a long time. Fire resistant clothing for fire brigades or common folk until the late sixties or early seventies. A couple hundred years after methods were discovered to prevent flames from lighting up fibers. The last place I lived at my neighbor was a retired fire captain who'd often chat with me over a drink and I learned quite a bit about fire and fire safety from him. He began his service in the late sixties and retired in the early 2010s. Sadly he passed due to cancer a couple years ago. One of his sons had just gotten married in the midst of the pandemic and his wife was due to have their first child. He and his wife had already become grandparents with their older son and daughter but a new baby is always a delight. He was really looking forward to meeting his new grandson.No fire repellent built in in those days.