Components of severity	Classification of asthma severity ≥ 12 years of age*
	Intermittent	Persistent-mild	Persistent-moderate	Persistent-severe
Impairment
Symptoms	≤ 2 days per week	> 2 days per week, but not daily	Daily	Throughout the day
Nighttime awakenings	≤ 2 times per month	3 to 4 times per month	> Once per week, but not nightly	Often 7 times per week
Short-acting beta agonist use for symptom control (not for prevention of exercise-induced bronchospasm)	≤ 2 days per week	> 2 days per week, but not more than once per day	Daily	Several times per day
Interference with normal activity	None	Minor limitation	Some limitation	Extremely limited
Lung function	Normal FEV1 between exacerbations; FEV1 >80 percent of predicted; FEV1/FVC normal	FEV1 ≥ 80 percent of predicted; FEV1/FVC normal	FEV1 > 60 percent but < 80 percent of predicted; FEV1/FVC reduced 5 percent	FEV1 < 60 percent of predicted; FEV1/FVC reduced >5 percent
Risk
Exacerbations requiring oral systemic corticosteroids	0 to 1 per year†	≥ 2 per year†	≥ 2 per year†	≥ 2 per year†
	Consider severity and interval since last exacerbation; frequency and severity may fluctuate over time for patients in any severity category; relative annual risk of exacerbations may be related to FEV1