Why do you cough when you inhale smoke?

I cough all of the time with my ashtma and feel like my chest is being crushed. It is quite annoying, actually! I cannot even enjoy a movie because I cough so much. When I have an Asthma attack, I cough uncontrollably and it is hard to stop even with my rescue inhaler. My mother had asthma worse than I do and she never coughed. I think it varies from person to person.