An indoor air quality complaint in an office rarely turns out to be a toxic exposure. It usually turns out to be a ventilation system nobody has looked at in three years, and a maintenance record nobody can produce.
The standard that applies to buildings
8 CCR section 5142 covers mechanically driven heating, ventilating and air conditioning systems providing minimum building ventilation. It requires outdoor air quantities meeting the Building Standards Code in force when the building permit was issued, operation of the system continuously during working hours, an annual inspection, documented maintenance, and records kept five years.
That five-year record is the first thing requested after a complaint, and it is the first thing missing. Filters changed on an invoice from a vendor are not by themselves an inspection record; the record has to show that the system was examined and found to be operating as designed.
Do not cite the wrong section
Section 5143 sets general requirements for mechanical ventilation systems — local exhaust ventilation, the kind that captures a contaminant at its source. It is not the office ventilation standard, and citing it in an office IAQ report is a tell that the report was assembled from a template.
What an investigation should actually do
- Take the complaint history first: who, where, when in the day, when in the week, and what makes it better
- Walk the space with the drawings, then walk it again with the ceiling tiles up
- Measure carbon dioxide as a ventilation indicator, plus temperature and relative humidity, at the complaint locations and at a control location, over time rather than once
- Look for the obvious sources before the exotic ones: a blocked outdoor air damper, a fan running on a schedule that ends at four, an exhaust intake beside a loading dock, water damage above the ceiling
- Sample for specific contaminants only where the walkthrough gives a reason to; a broad screening panel with no hypothesis produces numbers and no answers
Carbon dioxide deserves a note. It is not a toxic concern at office concentrations. It is a proxy for how much outdoor air is reaching people, and its usefulness is in the pattern through the day, not in a single reading held up against a threshold.
Michael Karl McNeil, registered industrial hygiene professional.
Michael Karl McNeil 