Specifications

1
1.0 INTRODUCTION
Between July 10, 2001 and August 2, 2001, Charlotte Ferguson, Masters student in Occupational
Hygiene from McGill University, conducted a chemical exposure assessment at Langley
Memorial Hospital (LMH) located at 22051 Fraser Highway in Langley, British Columbia. The
assessment included a walk-through survey and sampling for formaldehyde in the dirty core area
(outside operating rooms) and nitrous oxide in the maternity wards.
This project, funded by the WCB BC is part of a chemical exposure assessment for the South
Fraser Health Region (which includes LMH). The purpose of the project was to quantify the
nurses’ exposure to formaldehyde and nitrous oxide and compare it to the WCB OF BC exposure
limits. The British Columbia (BC) limit for formaldehyde is an 8hr exposure limit (EL) of 0.3
ppm and a ceiling EL of 1.0 ppm. An 8-hour exposure limit means the time weighted average
(TWA) concentration of a substance in air which may not be exceeded over a normal 8 hour
work period. Ceiling limit means the concentration of a substance in air which may not be
exceeded at any time during the work period. Nitrous oxide has an 8hr EL of 25 ppm with no
ceiling or short-term exposure limits. Occupational Health and Safety (OHS) Regulation 5.49
states that if only 8-hour exposure limit is provided then a worker’s exposure to the substance
does not exceed three times the 8-hour exposure limit for more than a total of 30 minutes during
the work period and five times the 8-hour exposure limit at any time (3X and 5X excursion
limits).
2.0 LITERATURE REVIEW
2.1 Formaldehyde
Formaldehyde is a volatile organic compound (VOC). When levels in the air are greater than 0.1
ppm it can cause burning sensations in the nose, throat and eyes, watery eyes, nausea, coughing,
chest tightness, wheezing, skin rashes and allergic reactions (EPA, 1997).