Is there a way to find incidence data in the US for Respiratory Diseases?
The National Health Interview Series through IPUMS NHIS has a variety of variables available related to respiratory diseases. For example, the variable CRONBRONYR identifies sample adults whom a doctor or other health professional had diagnosed with chronic bronchitis during the past 12 months. This is just one of many variables available (depending on your time frame for analysis). There are other variables related to asthma and emphysema as well. You can browse all of the available variables and samples here.