Inclusion Criteria:  Age 37-90 FDNY rescue and recovery worker. Male* Documented WTC exposure. Consented/Enrolled in the FDNY WTC Health Program Subjects are willing and able to consent for themselves to study enrollment Subjects are willing and able to participate in study procedures Are able to perform their activities of daily living independently Are either light duty or retired FDNY Firefighters Spirometry available within the last 24 months, and at a post-9/11 visit. Have means to accommodate transportation to/from in-person visit Are able to attend a single visit at the CTSI (462 1st Avenue, C & D 4th Floor) Pre-9/11 spirometry with FEV1%predicted ≥LLN and if not available 1st -post 9/11 spirometry with an FEV1 >80% predicted. Exposure at the WTC-site within 2 weeks of the 9/11/2001 Entered WTC-HP before the site closure on 7/24/2002. Serum from their first post 9/11 WTC-HP visit is available in the FDNY WTC biorepository and may be assayed Are not currently being treated for malignancy Subjects will either need to be defined as having WTC-AHR, WTC-GERD, WTC-BE or be designated controls as per the following additional inclusion criteria are specific to the WTC-aerodigestive disease that the subjects have AHR--A positive methacholine (PC20<16) and/or positive bronchodilator response (ATS/ERS guidelines: improvement of FEV1 by 12% and at least 200mL) at least once post-9/11.[95, 96]No recorded positive AHR testing prior to 9/11  GERD Inclusion Criteria  Erosive esophagitis LA grade C or D (as described on endoscopy), OR Stricture or Barrett's esophagus on endoscopy, OR Esophageal acid exposure time >6% on a pH or pH impedance study  19. BE Inclusion Criteria  Columnar epithelium lining ≥1 cm of the distal esophagus. AND Histologic examination of biopsy specimens from that columnar epithelium must reveal intestinal metaplasia characterized with goblet cells.  Exclusion Criteria:  Unwilling to complete an informed consent. Not enrolled in the WTC-HP Do not meet eligibility criteria for AIM 1 or did not have serum available in the biorepository from the first post 9/11 WTC-HP visit. Have pre-existing and documented conditions or concurrent diagnoses, including (and not necessarily limited to) active cancer, severe heart disease, significant cognitive impairment, eating disorders, significant psychiatric illness, end-stage COPD, severe pulmonary hypertension, or organ transplant. High dose steroid (>20mg prednisone or equivalent) or other hormonal treatments/chemotherapy use in the last month, including testosterone supplementation. Life-expectancy < 6 months Female*