Bronchodilation can be described as the expansion of the bronchial air passages in the respiratory tract. A bronchodilator is a substance that dilates the bronchial tubes resulting in decreased resistance in the respiratory airway and increased airflow to the lungs. From a subjective standpoint, this effect makes it feel as if has become significantly easier and more comfortable to breathe.
Bronchodilation is often accompanied by other coinciding effects such as stimulation. It is most commonly induced under the influence of moderate dosages of stimulant compounds, such as amphetamine,  methamphetamine, and cocaine,  . These compounds were historically used often for treating asthma but are now rarely if ever, used medically for their bronchodilation effect.
- Dominic Streatfeild (17 June 2003). Cocaine: An Unauthorized Biography | https://books.google.com/books?id=9ceLzaeHsZAC&pg=PA110&lpg=PA110&dq=Bronchodilation+cocaine&source=bl&ots=VLNaxDbv2p&sig=3TynN4xCUoVyBbwaIxZAFsLHKP4&hl=en&sa=X&ei=0BBZVbsMi6k237yBuA8&ved=0CCYQ6AEwAQ#v=onepage&q=Bronchodilation%20cocaine&f=false