Hi Am 38 Yrs And Have Had A Problem With

Hi am 38 yrs and have had a problem with breathing especially at places with dust and smoke, In places with AC ( room or in the car) I start coughing. when I get a flue or cold it takes so long to end and have blocked and a running nose. A doctor said I could have had asthma when I was young. What tests can I do, or how can I know my problem