After the initial screening measurement has been taken, follow-up action should be taken according with the following recommendations.
Screening Measurement Recommendation
*0.0-4.0 0-0.02 *
*4.0-10 0.02-0.05 *
You have a relatively low probability of avoidable health risk. Follow-up measurements are probably not needed, but may be made at your discretion.
You should perform long-term measurements as soon as practical.
You should perform short-term follow-up measurements as soon as possible.
You should perform short-term follow up measurements promptly and call PA DEP at 1-800-23RADON
The results of follow-up measurements will enable a homeowner to make a well-informed decision about possible health risk and the need for remedial action. As the decision to remediate often involves spending a significant amount of money, follow-up measurements should be reliable and reproducible estimators of the actual or maximum potential exposure of the occupants.
SUGGESTED METHODS FOR FOLLOW-UP MEASUREMENTS
Follow-up measurements should be performed in at least two locations within the home, preferably on the lowest livable level, the basement and on one other living level. The result from each location should be averaged to obtain an overall average for the living areas of the home.
If the result of the screening measurement is between 4 pCi/L(0.02 WL) and 10 pCi/L(0.05), a long term follow-up measurement to estimate the overall annual average concentration should be made. The occupant should consider using a measurement device, such as an alpha-track detector (ATD) or long- term electron ion chamber (EIC) to estimate the average concentration in the living area. An alternative, but less accurate method for estimating annual average is to use the average of short-term measurements made at particular intervals. The year-long measurement is more reliable for determining long-term exposure, because short-term and seasonal variations will be incorporated into the annual estimate. All measurements made to estimate annual averages, whether 12-month integrated or a series of periodic measurements should be made under normal living conditions rather than “closed house conditions”. The results of the measurements in each living area are averaged to estimate the annual average.
If the result of the screening measurement is between 10 pCi/L (0.05 WL) and 100 pCi/L (0.50 WL), a short-term follow-up measurement should be made as soon as practical. A short-term follow-up measurement will minimize additional exposure while providing reproducible results that can be utilized to estimate average concentration.
NOTE: All screening and follow-up measurements are made in accordance with “Protocols for Radon and Radon Decay Product Measurements in Homes”, EPA 402-R-93-003, June 1993