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Classification of Asthma Severity: Method of Canadian Consensus28
| Severity | FEV1/PEF | Short-acting beta-agonist use | Near-fatal episode | Hospital admission | Nighttime symptoms | Limitation of daily activities |
| Severe | <60% | Q 2 to 4 hr | + | + | +++ | +++ |
| Moderate | 60% to 80% | Q 4 to 8 hr | - | - | + | +/++ |
| Mild | >80% | <8 h | - | - | -/+ | -/+ |
Symptom: not reported, - ; reported, + ; reported more often, ++ and +++
FEV1: forced expiratory volume in one second; PEF: peak expiratory flow
