here is the website that explains the impairment listing for CF:
<a target=_blank class=ftalternatingbarlinklarge href="http://www.ssa.gov/disability/professionals/bluebook/3.00-Respiratory-Adult.htm#3.04%20Cystic%20fibrosis">http://www.ssa.gov/disability/...04%20Cystic%20fibrosis</a>
<a target=_blank class=ftalternatingbarlinklarge href="http://www.ssa.gov/disability/professionals/bluebook/3.00-Respiratory-Adult.htm#3.04%20Cystic%20fibrosis">http://www.ssa.gov/disability/...04%20Cystic%20fibrosis</a>