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Investigation Indoor Air Quality Complaints – School in Oakland

“Our school worked with the HVAC technicians to repair the system issues that your report found, and we upgraded our filters. Recently during the fires, we tested the air internally 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 because several staff members were experiencing respiratory problems. The problem had grown so bad for one employee that he was wearing a particulate respirator to work every day to stave off asthma attacks. They were concerned about the effect the air quality was having on the student body and staff alike. There was also concern that the proximity of the building to high-traffic railroad tracks had a negative impact on the indoor air quality as well.

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 of the school to determine how the facilty was being utilized and this included a visual investigation of the HVAC system as well.  Interviews with staff were conducted and a review of the building history which also helped to identify any areas of concern.

IAQ School Results

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

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 HVAC system on the roof revealed that they had three HVAC package units and only one was actually in functioning order. The unit that was functioning had the air intake directly over the desk of the staff person most negatively affected, who had resorted to wearing the respirator to work. So, this unit was probably drawing the dusty air toward that office.

Of the other two HVAC units that were not running, one of those units had the damper for the economizer stuck open. Heated air from inside the building was escaping from the unit so that not only was it not serving to ventilate but was a big energy waster.  This unit was the one that was supposed to serve a bank of offices which all had 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 wouldnot be able to remove fine particulates associated with exhaust from the nearby train yard. Additionally, all three units had damage to pre-filter screens that would 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 not only resolved the air quality complaints, but made the building a refuge from poor exterior air quality. Improved filtration now protects the occupants from smoke from wildfires and exhaust from vehicles and nearby industry.


Project Team Lead Environmental Inspector, Laurel Cain






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