Collection of quantitative data to demonstrate the accuracy (bias) and precision (repeatability) of the Apieron INSIGHT(tm) eNO Breath System as compared to the FDA cleared NIOX eNO Breath System when testing is performed by asthma patients.

A non-randomized, prospective study of up to 150 subjects with asthma. Patients will perform eNO testing with the Apieron INSIGHT(tm) eNO system and the NIOX eNO system at the physician's office/clinic after a short demonstration and training by a healthcare professional trained in the use of the devices. Exhaled NO testing involves inhaling to lung capacity, and then performing a controlled exhalation into a mouthpiece connected to each of the Apieron INSIGHT(tm) and NIOX systems. Patients will perform an eNO measurement with the Apieron INSIGHT(tm) system and with the FDA cleared NIOX system for the accuracy portion of the study. Patients will perform 2 sequential eNO measurements on each system for the precision part of the study. Subjects that measure eNO values over 100 ppb will be asked to repeat 2 sequential eNO measurements on each system.

Inclusion Criteria:

• Age 5 or older
• Pre-existing diagnosis of asthma
• Non-smoker

Exclusion Criteria:

• Chronic inflammatory lung disease other than asthma
• Medical conditions that preclude hand-eye coordination

Up to 150 asthma patients recruited from the site center's population of patients.