unavoidable, high-efficiency particulate air (HEPA) filters should be installed in the exhaust leading from
the room to the general ventilation system. Air from TB bedrooms and treatment rooms in new or
renovated facilities should not be recirculated into the general ventilation system.
3. Exhaust air quantity must be 10% greater than the supply air. It is further recommended
that the exhaust system should serve only the TB rooms and not be part of the general exhaust system. If
this is not practical, then use of the general exhaust system is acceptable provided appropriate precautions
are taken to assure that these systems are adequately designed, installed, balanced, and maintained.
These requirements result in providing additional outside air through the air handling system which then
impacts heating and cooling capacities for both air side and primary equipment. In all applications, thermal
load calculations or occupancy of the space may require a higher air change rate.
4. Rooms should be under negative pressure with respect to adjacent areas when
occupied by a patient with S/KI TB.
5. Anterooms are not necessary for S/KI TB patient bedrooms.
6. The direction of the airfiow for TB rooms shall be monitored daily when an S/KI TB patient
is occupying the room. When not in use by S/K TB patients, the directional airflow will be checked
monthly. The method of testing for directional airflow in the S/KI TB rooms is at the discretion of the
facility, but must be of an acceptable standard. This would include such methodolosxies as smoke tube
testing or an airflow gauge.
7. The number of air changes per hour in these rooms should be checked yearly at a
minimum. This may need to be more frequent based on facility risk assessment and recommendations of
the Environmental and Infection Control Committee. In addition, the number of air changes per hour
should be checked after any maintenance to the airflow system.
8. In rooms where patie nt turnover is expected, use CDC guidelines (MMW2 , October 28,
1994, Vol. 43, No RR-13) for air changes per hour to determine time required for removal of airborne
contaminants before the next patient occupies the room vacated by a patient with S/KI TB.
9 When in use by S/KI TB patients, doors in negative pressure rooms must remam closed,
except for entering or exiting the room. Proper airflow and pressure differentials between areas are
difficult to control because of open doors, movement of patients and staff, temperature, and the effect of
vertical openings. Air pressure differentials can only be maintained in completely closed rooms. An open
door reduces or eliminates the desired effect of negative pressure rooms. Whether windows are needed in
doors to S/KI TB patient bedrooms is a local decision.
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