∙ (Inclusion Criteria: Subjects must meet all of the following inclusion criteria to be eligible for enrollment into the trial)

• Outpatients of either gender, age \> 18

• Willing and able to give informed consent and adhere to visit/protocol (Consent must be given before any study procedures are performed.)

• Subject has no diagnosed pulmonary conditions

• Subject has not smoked in the previous 5 years

• Smoking history, if any, is less than or equal to 5 pack-years

• No history of using other inhaled products more than 1/week for \> 1 year

• In-patient or outpatients of either sex, age \> 18

• Willing and able to give informed consent and adhere to visit/protocol

∙ And one of the following:

• Patients who are scheduled to receive a red cell transfusion for anemia.

• Patients who are scheduled to undergo therapeutic phlebotomy to treat erythrocytosis or polycythemia

• Healthy volunteers undergoing voluntary whole blood donation (healthy volunteer inclusion criteria noted above)

• In-patient or outpatients of either sex, age \> 18

• Willing and able to give informed consent and adhere to visit/protocol

∙ And one of the following categories (ILD, Dyspnea, CTEPH, or Healthy):

• Interstitial Lung Disease or Dyspnea

‣ Physician diagnosis of Interstitial Lung Disease by a pulmonologist using established criteria or physician referral of patient with dyspnea

• OR

• Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

‣ Patients with a diagnosis of CTEPH, defined as mean PA pressure \>20 mmHg with a pulmonary vascular resistance \>2 WU and pulmonary capillary wedge pressure ≤15 mmHg at right heart catheterization with evidence of chronic thromboembolic disease on clinical imaging after 3 months of anticoagulation

⁃ Scheduled for pulmonary thromboendoarterectomy (PTE) surgery and willing to re-turn 3-6 months after for optional follow-up scans

• OR

• Healthy Volunteer (criteria noted above)

• In-patient or outpatients of either sex, age \> 18

• Willing and able to give informed consent and adhere to visit/protocol

∙ And one of the following categories (Acute or Chronic)

• Acute Pulmonary Embolism

‣ Patients presenting with acute PE 24-48hrs post-admission

⁃ Willing to return after 3-6 months of anti-coagulation therapy

• OR

• Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

‣ Patients with a diagnosis of CTEPH, defined as mean PA pressure \>20 mmHg with a pulmonary vascular resistance \>2 WU and pulmonary capillary wedge pressure ≤15 mmHg at right heart catheterization with evidence of chronic thromboembolic disease on clinical imaging after 3 months of anticoagulation

⁃ Scheduled for pulmonary thromboendoarterectomy (PTE) surgery and willing to re-turn 3-6 months after for optional follow-up scans