Table 2. Comparison of selected environmental controls for NPIRs of regulations and guidelines.

	Korean regulation14	CDC7	ASHRAE13	AIA11
Room designation	NPIR	AIIR	AIIR	AIIR
Total ACH	Prefer ≥12 (minimum ≥6)	Prefer ≥12 (minimum ≥6)	>12	≥12
In-room HEPA recirculation allowed?	Yes	Yes	No	No
Total ACH can include HEPA recirculation?	Yes	Yes	No	No
Minimum outside ACH	2	Different among selected areas	2	2
Minimum room pressure differential	≥2.5 Pa	≥0.01" W.G.	≥0.01" W.G.	≥0.01" W.G.
Upper-air or in-duct UVGI allowed?	Not addressed	Yes, but not in lieu of ventilation	Not addressed	Yes, but not in lieu of ventilation
Anteroom required?	Yes	No	May be desirable	Noted as general option, required for protective environment isolation rooms for airborne infection isolation
Minimum anteroom ACH	Not addressed	10	10	10
Monitoring of negative pressure	Install manometers	Check daily while being used for isolation	Not addressed	Not addressed

Modified from Curry International Tuberculosis Center. Tuberculosis infection control: a practical manual for preventing TB, with permission of Curry International Tuberculosis Center9.

NPIR: negative pressure isolation room; CDC: United States Centers for Disease Control and Prevention; ASHRAE: American Society of Heating, Refrigerating and Air Conditioning Engineers; AIA: American Institute of Architects; AIIR: airborne infection isolation room; HEPA: high efficiency particulate air; ACH: air changes per hour; HEPA: high efficiency particulate air; UVGI: ultraviolet germicidal irradiation.