Working indoors does not always mean sitting in a cubicle or walking up and down the halls of school. Many of us work in potentially hazardous environments without realizing, as outlined in this case study. In a municipal garage that services heavy diesel equipment, office staff reported complaints of experiencing discomfort related to dry conditions and expressed concerns that the newly installed emissions ventilation system was insufficient. CM3 was contacted to coordinate and complete an indoor air quality assessment.
The assessment was comprised of a site investigation, the collection of data for general air quality characteristics, and air sampling for by-products of diesel combustion that may pose an exposure risk to building occupants.
Measurements of air quality parameters included Elemental Carbon (soot), Organic Carbon (OC), Carbon Dioxide (CO2), Carbon Monoxide (CO), Sulphur Dioxide (SO2), Nitrogen Dioxide (NO2), Nitric Oxide (NO), Formaldehyde (CH2O), Airborne Particulate (PM), Temperature (OC), and Relative Humidity (%RH).
Based on the site reconnaissance it was determined that the majority of the by-products of diesel combustion were found to be below workplace exposure criteria, with some at nearly indetectable levels, which indicates that the exhaust systems were functioning properly. However, over the course of the investigation Temperature levels were observed to increase, and %RH levels were found to decrease, resulting in levels below industry standards. Temperature and relative humidity are considered comfort parameters and each worker may experience varying levels of comfort.
The low relative humidity measures obtained were consistent with the concerns raised by occupants.
In order to mitigate the concerns related to thermal conditions, simple means such as passive ventilation by opening garage doors and windows were implemented, and administrative controls such as temporary vehicle shut down and managing operations were implemented. Long-term solutions such as upgrades to the mechanical HVAC system were considered and evaluated by a mechanical engineering team.
