Does asthma cause hypoxia? what is the oxygen saturation in people who have asthma?

It can: Asthma can reduce the area of the lung available for co2/oxygen exchange and can do so with variable intensity during an asthma attack. Given a normal o2 % of 94-100, I have seen levels below 50% recorded but patients are usually quite symptomatic below 90%. When an attack is passed and the patient relaxed, the levels return to normal with work of breathing decreased to normal.