Specifications

19
is 10 cfm. The balance report also contained the flow rates for the two exhausts in the main
room, which were 203 cfm each and the bathroom exhaust was 127 cfm. This gives a total of 9.9
air changes per hour for the room if the door was closed at all times.
6.0 DISCUSSION
6.1 Formaldehyde
The results from the silica gel tubes and colorimetric tubes indicate that the levels of
formaldehyde in the dirty core did not exceed the WCB OF BC 8 hour exposure limit of 0.3
ppm.
In the summer months, only two of the six operating theatres are in use meaning that fewer
nurses are working and therefore it is more likely that a nurse will dispense formalin more than
once in a day. These measurements represent a type of worst case scenario and the results
indicate that the general exhaust ventilation in the area, combined with the small and infrequent
amount of formalin dispensed, is sufficient to keep exposures below the allowable limits.
One concern in the formalin dispensing area is the leaking spigot on the formalin bottle. In an
effort to keep worker exposures to formaldehyde vapours as low are reasonably achievable
(ALARA) below the WCB of BC exposure limit, it is important to ensure that the spigot does not
leak and that an exposure control can be established for this suspected human carcinogen.
6.2 Nitrous Oxide
The data collected by the Miran indicate that the concentration of nitrous oxide in the
environment fluctuate wildly as nitrous oxide is used. The Medigas 3010 data indicate that when
the mother inhales and exhales into the mask the nurses exposure is relatively low, however,
when the mother removes the mask from her face, between contractions, she is off-gassing into
the room. Spikes were noted in the nurses exposure when working near the mother’s face
including when starting an IV or standing close to the mothers head and talking to her.