Table 2. Tiered protection standards for different areas.

Area	Category	Surgical mask	N95 mask	Hat	Goggles	Sterile rubber gloves	Protective face screen	Overall	Isolation gown	Protective clothing	Shoe covers	Waterproof boots	Positive pressure headgear
Green area	General protection	○		○				●
Blue area	First tier protection	●		●	○	●	○	●	○
Yellow area	Second tier protection	○	●	●	●	●	●	●	●	○	●
Red area	Third tier protection	●	●	●	●	●	●	●	○	●		●	○

●, need to master; ○, need to understand.