It is well known that herbs have health benefits and that vapors can help with various breathing problems. Many people when they have had a cold or chest infection will have found themselves with faces over a bowl of hot water with menthol or eucalyptus mixed in, the relief is worth it even if the steam burns a little. There are more modern ways though to deal with colds, chesty coughs and even long term conditions like Asthma and Hayfever. The solution is still using herbs and vapors though but in a practical way that can be used long term.
A vaporizer simply heats herbs to release vapors, you may think that heating herbs would simply burn the herbs and release smoke, which is the last thing you want if you have a cough or suffer from Asthma. Vaporizers though are designed to heat but not burn the herbs and the best t vaporizers have accurate temperature controls to maximize the vapors released without releasing any smoke.
Smoke of course is bad for you and can be cacogenic but vapors are safe and have health benefits.
Mint and Eucalyptus are the herbs you may be most likely to want to use, they work well mixed and you may want to add some Thyme as well. This combination will be great for breathing problems due to constriction of breathing passages such as the bronchial tubes and will help to loosen phlegm.