45e3b46b___Knowing_How_Bad_an_Attack_Is__of_your_child_s_asthma_attack_Severe_attack
[Factor] Peak expiratory flow [Mild attack] 80% to 100% of personal best [Moderate attack] 50% to 79% of personal best [Severe attack] 
Less than 50% of personal best
Asthma in Children: Knowing How Bad an Attack Is