D.C. Mun. Regs. tit. 22, r. 22-B3239
Each facility shall be well ventilated through the use of windows, forced air, or both.
Both natural and mechanical ventilation and exhaust shall comply with the provisions of the 1996 BOCA International Mechanical Code (Heating, Air Conditioning and Refrigeration), and all other applicable District laws and regulations.
If only a natural ventilation is relied upon, the total open area shall equal at least 4% of the floor area served.
When an open area other than windows is included in the required area, at least fifty percent (50%) of the required area shall be furnished by a window or windows.
Ventilating skylights may be permitted to furnish not more than fifty percent (50%) of the required open area.
Mechanical ventilation shall be provided in accordance with the latest edition of "Pressure Relationships and Ventilation of Certain Areas of Long Term Care Facilities" from the American Institute of Architects Committee on Architecture for Health, with assistance from the U.S. Dept. of Health and Human Services.
In each area in which food or drink is served, a minimum of two (2) cubic feet per minute air changes of outside air per hour shall be provided.
Each respiratory isolation room and connected bathroom shall be ventilated with negative pressure that shall prevent contamination of other areas.
Each cooking unit that creates smoke, steam, gases, fumes, odors, vapors, or excessive heat shall be hooded and vented or locally vented to the outside air by forced draft in accordance with Title 23 of the DCMR.
Each small burner that is used intermittently for short periods of time such as warming equipment, a bread toaster, coffee urn, and radiant cooking units shall not be vented unless it or a combination of the units create a nuisance.
Each cooking unit ventilation hood shall be provided with an automatic fire extinguishing system.
Each ventilation and exhaust system shall be maintained in good operating order.
Air filters shall be provided and shall be properly cleaned, regularly replaced, and maintained in each circulating air system, including each individual air conditioning unit in each resident's room.
D.C. Mun. Regs. tit. 22, r. 22-B3239