Commercial Buildings

More and more administrative buildings are being tested for radon exposure to employees.  This is being done either as a proactive measure by the employer or complaints by employees.  Although OSHA has exposure guidelines less stringent than EPA's recommendations, EPA's guidance is being interpreted as reasonably achievable for workplace exposure.  Radon testing is also becoming very commonplace in apartment buildings as a means to avoid landlord/tenant liability issues.   

Radon can enter large buildings just as easily as homes. In fact, the entry can be quite high if the heating ventilation and air conditioning system (HVAC) is not balanced.  The effects of the HVAC system on radon entry are two-fold:

• Large buildings are typically designed to have fresh air introduced into the building via the HVAC system which would serve to positively pressurize the building and reduce radon entry from the soil.  However, energy management strategies at times reduce or even shut off the addition of fresh air, either deliberately or when control components fail. 

• Also, large HVAC systems become unbalanced for a given room where more air is drawn out of the specific room than is supplied. This causes that particular room to be under negative pressure that can draw radon in, if the room is in contact with the soil. 

However, when these two conditions occur the HVAC system is still operating and recirculating air within the building.  The simple air movement within the building, regardless of whether fresh air is being added or the system is balanced can still significantly reduce the levels of radon decay products within the rooms, and hence risk exposure, even if the radon levels are elevated. 

The following photogalleries provide some examples where radon decay product measurements were helpful in either better characterizing the risk or evaluating air filtration technology. 

Click on thumbnail photos to view pictures more clearly.

Hotel This is a hotel where previous radon measurements indicated a problem in an employee area. Follow-up testing indicated that although radon was elevated, radon decay products were low, thereby avoiding mitigation costs in the several thousands of dollars.	Paper Handling Facility Previous measurements had indicated a potentil radon concern, Follow-up measurements indicated that although radon was elevated, the radon decay products were below the guideline. This was due to high air circulation rates and air filtration equipment in place to control paper dust levels.	Impact of Console Air Filter on Single Room A facility had a single room within it where radon levels were elevated. Due to security, the employee worked there under closed conditions. Follow-up measurements indicated that radon decay levels were even higher than what radon measurement would indicate. A small $120.00 filter was added.	Impact of Console Filter Unit on EF The small console unit in a small area was able to significantly reduce percentage of radon decay products in the air. In addition to reducing exposure, the employee greatly appreciated the "feel" of the room after the filter was added.

Discussion:  Often there are aspects of the building that are already in place that is reducing radon decay product exposure, such as:

• Air circulation systems (HVAC)

• Gross particulate filters

• Fine, localized air filters

With a radon gas measurement only, the benefits of these systems are not detected.  In assessing the impact of these ancillary building systems, one has to ascertain if these systems operate continuously, or certainly if they operate during occupied time periods.  If the answer is yes, then a decision made on radon decay products is appropriate, provided information is provided to the client that these systems are to be maintained, just like a regular radon mitigation system.  In cases where a perceived benefit is obtained (such as the addition of the air filter to the example above), it is likely that occupants will make the effort to maintain such a system-perhaps, even to a greater degree than they would maintain an active soil depressurization system.

Caution: When doing follow-up measurements using radon decay product levels as a criteria it is important to also measure radon.  This insures that the lower radon decay product levels are a function of lower equilibrium factors and plate-out, rather than an a lower radon gas level during the time of the follow-up measurement.  That is why PGL provides devices through its manufacturing partners that measure BOTH radon and radon decay products!

Send mail to Progenyltd@aol.com with questions or comments about this web site.
Copyright © 2004 Progeny Group, Ltd.
Last modified: 06/05/08