A 23 year old man presents to the emergency department with cough, wheezing, and dyspnea. He has a history of asthma, and has had no hospital visits in the last year. He does not use a puffer regularly. He is talking in full sentences. On exam, he is tachypneic at 28 breaths per minute, but otherwise using no accessory muscles. His HR is 110 beats per minute, with an O2 saturation of 94%. His peak flow is 65% of his predicted value. He has wheezing on auscultation. What is the severity of his asthma exacerbation?