Investigation: Indoor Air Quality Complaint – Oakland School

“Following HBS report guidance, our school worked with the HVAC technicians repairing issues and upgrading our system filters. We tested the interior air during the recent fires and found that we were in excellent shape. Our guidance counselor is no longer wearing a respirator to work!

 Thank you for all of your help.” 

-HR Manager

Indoor Air Quality Complaints at School – Project Summary

Healthy Building Science was contacted by an Oakland based school for continuing education because several staff members were experiencing respiratory problems. The problem had grown so severe for one employee that he wore a particulate respirator to work every day to stave off asthma attacks. They were concerned about the effect poor air quality was having on the student body and staff alike. There was also concern that proximity of the building to high-traffic railroad tracks was negatively impacting indoor air quality.

School Indoor Air Quality (IAQ) Assessment Process

The indoor air quality (IAQ) assessment included air sampling for mold spores, volatile organic compounds, formaldehyde, respirable particulates, carbon dioxide, relative humidity and temperature. A visual inspection was conducted to determine how the facility was being utilized; this included visual investigation of the HVAC system as well.  Interviews were conducted with staff and the building history was reviewed helping to identify additional areas of concern.

School IAQ Results

Particle count measurements of airborne respirable particulates were the telling piece of data. One of the many activities in the building was a weekly wood shop class, teaching students to use power tools and basic construction skills. While useful skills to learn, the space was not equipped to handle dust generated by the class equipment.

Particle counts measured in the classroom and adjacent common kitchen revealed particulate concentrations much higher than recommended by the EPA.

HVAC School IAQ Investigation

Damaged pre-filter screen on HVAC unit allows moisture to enter the system.

Investigation of the rooftop HVAC system revealed three HVAC package units where only one was actually in functioning order. The functioning unit had the air intake directly over the desk of the staff person most negatively affected, tho one who had resorted to wearing a respirator to work. This unit was drawing dusty air toward that office.

Of the two HVAC units that were not running, one of those had the economizer damper stuck open. Heated air from inside the building was escaping from the unit so not only was it failing to ventilate, but also wasting energy.  This unit was supposed to serve a bank of offices where we had detected high CO2 readings, indicating insufficient air flow.

HVAC2 -HVAC School IAQ Investigation

Wetting of HVAC filters can lead to microbial growth contaminating the system.

The HVAC package units all had low efficiency air filters installed which could remove larger particles from the air, but would not be able to remove fine particulates associated with exhaust from the nearby train yard. We discovered all three units also had damage to pre-filter screens that should prevent rain and mist from entering the unit and wetting the air filters which can lead to mold growth.

IAQ School Assessment Conclusion

Improvements made to the HVAC system resolved the air quality complaints and made the building a refuge from poor exterior air quality. Improved filtration now protects the occupants from wildfire smoke, vehicle exhaust and nearby industry airborne pollutants.


Project Team Lead Environmental Inspector, Laurel Cain