I used to smoke, and I also have (very mild) asthma that was diagnosed prior to me starting to smoke. I always said that I could breath better after a cigarette and people would laugh at me. It never occurred to me that of the thousands of chemicals in a cigarette some of them might be geared specifically to "help" you take in more smoke, and by extension, more air after.
https://www.pharmacytimes.com/contributor/timothy-aungst-pha...