Graph of Carbon Dioxide Concentrations in the complaint area and outdoors during the monitoring period.

Several employees working in a department of a public building complained of respiratory symptoms, such as coughing and asthma flare-ups while at work. Clark Seif Clark, Inc. (CSC) was requested to investigate the area to determine if any indoor air quality deficiencies might have contributed to these symptoms.

CSC approached this assessment as follows:

• Interviewed department managers to obtain specific information about symptoms, building and office history, number of symptomatic employees, etc.
• Visual and moisture survey of office and heating, ventilation and air conditioning (HVAC) system servicing the office.
• Tested ventilation efficiency by monitoring temperature, relative humidity and carbon dioxide concentration for a one-week period.
• Collected dust for particle identification, allergen scan and Environmental Relative Moldiness Index (ERMI).

Result:The visual survey revealed that fresh air was not being supplied to the offices, and that air filtration was under-utilized. Furthermore, the offices were very dusty. The ventilation efficiency monitoring revealed low relative humidity throughout the measurement period, which can contribute to occupant discomfort. The dust sample analysis revealed the presence of allergens in concentrations presenting a moderate risk of respiratory symptoms. The ERMI sample revealed that the office was more moldy than more than 80% of US homes that were included in the American Healthy Homes Survey. A sample collected from the HVAC system revealed that mold growth was present on the cooling coils. Based on these findings, CSC recommended cleaning the HVAC system, installing a fresh-air intake for the HVAC system, and upgrading the HVAC system filtration. In addition, CSC recommended thoroughly cleaning the office to reduce dust accumulation, and to correct the cause of the presence of elevated allergen concentrations in the office.