After a while it was probably done on purpose with the intentions of relaxing and listening to visions sent during hallucinations from the gods or spirits. Medicine men may have experimented with small fires, and then large fires were made at night with the clan surrounding the fire. This may have occurred as far back as 30,000 B.C.
Egyptian scribes made the first recordings of fumigations with cyphiac. Cyphiac was, "according to Dioscorides, a mixture of various drugs, and as the Egyptians had made great advances in the use of spices, balms, and other odorous medicines, it is probable that these entered largely into their cyphi. As soon as men began to use warm baths, indeed, as soon as they made water hot, they would become acquainted with its vapor, and probably notice the soothing effect of breathing steam, and endeavor to turn it to useful account." (1, page 276)
So early on in human history mankind had access to fumigations of smoke and steam. While this may have originally been part of religious ceremonies, there came a time in the course of history, perhaps at some point in both Ancient Egypt, where it was realized that smoke could better used for medicinal purposes when the herbs were placed on heated bricks and inhaled this way. Sometime around the time of Jesus poeple in some nations learned how to control smoke by making crude pipes for inhaling herbs. So now people had use of several methods of inhaling medicines, including fumigations of smoke and steam, insents, pipes, and ultimately cigarettes.
The Ancient Greeks also describe fumigations, as Homer mentions them. And, much like the Egyptians learned to master smoke for medicinal purposes, the Greeks learned to master steam for medicinal purposes. Around 400 years after Homer Hippocrates mentions an inhaler-like device of which I describe in detail in this post.
When Greek wisdom made it's way to Rome, this wisdom traveled with it. When Roman knowledge made it's way to the Arabs, this wisdom traveled with it then too. So, despite most of our efforts on the study of inhalers made by man, the first inhalers were probably simple fumigations.
(1, page 276)
- Prosser, James, "The Therapeutics of Respiratory Passages," 1884, New York, pages 281-282