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testing with these corridor doors in their “as-used” position which is either normally open or
normally closed.

4. Isolation rooms may be equipped with auxiliary, fan-powered, recirculating, stand alone
HEPA filtration or UV units. These units must be running when smoke-trail tests are
performed.

5. Do not restrict corridor foot traffic while performing smoke-trail tests.

6. Negative pressure is accomplished by exhausting more air than is supplied to the isolation
room. Some HVAC systems employ variable air volume (VAV) supply air and sometimes
VAV exhaust air. By varying the supply air delivered to the space to satisfy thermal
requirements, these VAV systems can adversely impact the performance of a negative
pressure isolation room. If the isolation room or the corridor is served by a VAV system you
should perform the smoke test twice. Perform the smoke test with the zone thermostat
thermally satisfied and again with the zone thermostat thermally unsatisfied thus stimulating
the full volumetric flow rate range of the VAV system serving the area being tested.

Smoke:

Most smoke tubes, bottles and sticks use titanium chloride (TiCl4) to produce a visible fume. There is
no OSHA PEL or ACGIH TLV for this chemical although it is a recognized inhalation irritant.
Health care professionals are concerned about releasing TiCl4 around pulmonary patients. The
smoke released at the door undercut makes only one pass through the isolation room and is
exhausted directly outside. Isolation room air is typically not “recirculated.”

The CDC in the supplementary information to the 1994 TB Guidelines has indicated that “The
concern over the use of smoke is unfounded.” Controlled tests by NIOSH have shown that the
quantity of smoke that is released is so minute that it is not measurable in the air. Nonirritating
smoke tubes are available and should be utilized whenever possible.

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