A 33 year old woman presents to the emergency department with dyspnea. She caught a cold 3 days ago and has had a cough with wheezing. She has a history of asthma, and has had 2 hospital visits in the past year although no admissions. She has not been compliant with her puffers, although she sometimes uses her salbutamol. She is able to provide yes and no answers, but has trouble speaking a full sentence. On exam, she is tachypneic at 33 breaths per minute, and is using her accessory muscles. Her HR is 125 beats per minute, with an O2 saturation of 89%. Her peak flow is 35% of her predicted value. She has inspiratory and expiratory wheezing on auscultation. What is the severity of her asthma exacerbation?