Indoor Air Quality in Office Buildings: A Technical Guide

4. Initial Assessment

The initial assessment is a fact-finding exercise to document the complaint. During the initial assessment, problems are defined and their severity is assessed. Background information is collected that will be helpful in identifying possible pollutants and locating their sources, including information on the building itself, on the kinds of symptoms employees have been experiencing, and on the period of time over which symptoms have been experienced.

A copy of the floor plans is helpful, as observations can be recorded on them directly. The investigator should also review any documents available on the history of the building, including modifications -particularly recent ones. A person familiar with the building's HVAC system should be available to assist the investigation, and any persons required for access should be identified.

4.1 Initial Walkthrough

A walkthrough is needed to gain a first-hand, visual appreciation for the building's design, floor plan, and ventilation system. This walk-through should provide enough information to enable the investigator to form a hypothesis, perhaps recommend simple modifications, and formulate a plan for the subsequent investigation.

Minimal measurements are taken during an initial walkthrough. The investigator can use specific checklists or worksheets and may focus on a localized problem area.

Occupants should be interviewed, especially complainants. Information on symptoms, timing of onset and relief, and spatial patterns of complaints should be gathered in order to define the problem as completely as possible. The investigator should also note any obvious sources of internal or external pollutants.

4.2 Reviewing the Complaint Area

The following general indicators help to call attention to pollutant sources:

• odours (see Table 2)
• overcrowding
• unsanitary conditions
• dust
• moisture problems, visible fungal growth
• staining and discolouration of ceiling tiles, walls or carpets
• presence of chemical substances.

Table 2.
Odours as Problem Indicators in Office Buildings

Description	Problem	Complaints
Auto exhaust,diesel fumes	Carbon monoxide	Headaches, nausea,dizziness, tiredness
Body odour	Overcrowding, low ventilation rate (high carbon dioxide levels)	Headaches, tiredness, stuffiness
Musty smell	Microbial material, wet surfaces	Allergy symptoms
Chemical smell	Formaldehyde, pesticides, other chemicals	Eye, nose, and throat irritation
Solvent smell	VOCs	Odour, allergy symptoms, dizziness, headache
Wet cement, dusty, chalky smell	Particulates, humidification system	Dry eyes, respiratory problems, nose and throat irritation, skin irritation, coughing, sneezing
Sewage gas odour	Water traps dry in floor drains in washrooms or basement	Foul smell

Other activities involved in reviewing the complaint area include the following:

• Compare the original uses of the complaint area and surrounding rooms with the present use. Has occupant density increased? Have work areas been rearranged or converted to other uses? Has new equipment, such as computers, printers, photocopiers, or humidifiers, been added?
• Identify areas where remodelling, repair, or redecorating activities are in progress or have recently been completed. Check that proper control procedures are being used to isolate dust, paint fumes, and other off-gassing contaminants related to the activity.
• Check temperature and humidity to see that the complaint area is in the comfort range. Check for visible mould due to condensation, elevated humidity levels or water leaks.
• Check carbon dioxide as an indicator of ventilation adequacy in occupied areas. Carbon dioxide levels above 1000 parts per million (ppm) in office environments indicate that the ventilation rate is low and that other airborne contaminants are accumulating.
• Observe airflow patterns. Look for areas of poor mixing, short-circuiting (supplies and returns close together), and obstruction of supply and exhaust ducts.

4.3 Defining the Problem and Drawing Conclusions

At the conclusion of the initial assessment, it should be possible to identify:

• the nature of the complaints
• the number of occupants affected
• building system parameters that can be related - by timing, location, etc. - to the complaints
• possible HVAC deficiencies and general operating and maintenance conditions
• signs of occupant interference with the ventilation system
• obvious internal and external pollutant sources.

If the specific source of the problem has been identified and a solution proposed, the investigation will stop until the changes are implemented and the effect is evaluated. If a solution cannot be found or other problems have come to light, it is necessary to proceed with a more detailed investigation.