| Color | normal dusky cyanotic cyanotic on O(2) |
| Air movement | normal mild decrease moderate decrease marked (down) |
| Retractions | none mild moderate severe |
| Mentation | normal restless lethargic obtunded |
| Stridor | none mild moderate severe/obstructed |
Any category with score of 3,classify as severe. Taussig: Am J Dis Child 1975; 129: 790