Information on Radon Testing

Information On Radon Testing
Posted on 10/08/2019
October 7, 2019   

Dear Clyde Brown parents, families and caregivers: 

Prior to opening the new Clyde Brown Elementary the Elementary School Building Committee and the Millis Public Schools chose to voluntarily assess the presence of radon in the school. While such tests are not currently required to be performed under either federal or state regulations, both the United States Environmental Protection Agency (USEPA) and the Massachusetts Department of Public Health’s Radon Assessment Unit encourage radon testing in schools.

This letter is to update you and provide information regarding radon, a colorless, odorless gas that is in soil in Massachusetts and other states and can make its way into buildings from the ground unless precautions are taken. 

A total of eight radon sample containers were placed at selected locations throughout the School and one was positioned outside by Alliance Environmental Group. The containers were deployed for just over 90 hours (short-term event) and were then retrieved and submitted to an approved laboratory to be tested. The results ranged from not detected above the method detection limits (Outside sample) to a high of 17.6 pCi/L  in the Electric Room, not accessible to students.. In total, radon was detected above the recommended EPA action level of 4 pCi/L in seven of the eight indoor samples. Those results range from 4.6 to 6.1 pCi/L.  At this time we do not have any results in classrooms, which is why comprehensive results of the entire facility are needed. 

It is our understanding that radon exposure at these levels does not pose an imminent health risk to students or staff.  Consistent exposure for a significant number of years is what increases the risk of health issues.   

Now that the School is in daily use, it is recommended that a full survey be performed in accordance with the EPA guidance document referenced below. The data collected from this survey will be used to confirm current radon levels throughout the building. If these levels suggest radon mitigation is indicated, short-term measures will be proposed, such as, adjusting the HVAC operating parameters so that a slight positive pressure (relative to atmospheric pressure outside the school) is created, in order to reduce the ability of radon to enter the building.  We will also perform a sub-slab venting pilot test to develop full scale mitigation design parameters.  We intend to perform these tests as expeditiously as possible.  They will be conducted over several days, while the building is occupied. 

Longer term remediation, if warranted, typically involves the installation of venting systems that vent radon gas from the ground beneath the building to the atmosphere and the hazard eliminated.     

If you have any questions, please see the MA DEP Radon Section at
or US EPA at and 

We will continually update you on our findings and the progress of our efforts.  The health and safety of our children and staff are our utmost concern.  We intend to proceed according to science and as quickly as possible.  If you have any questions or concerns, please contact me.   


Nancy L. Gustafson
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