Less than .5 pCi/L
In this range, the radon levels measured in your home are practically the same as those found in outdoor air. However, if you make any structural changes or start to use a lower level of the building more frequently, you should test again.
From 0.5 to 1.9 pCi/L
In this range, there is little short-term risk. Outdoor radon levels are often comparable to these levels (see image below). However, because radon levels fluctuate daily as well as seasonally, you may want to retest during another season. Additionally, if you make any structural changes or start to use a lower level of the building more frequently, you should test again.
From 2.0 to 3.9 pCi/L
Each short-term test is a snapshot of conditions during the 3-7 days of testing (for a short-term test), so in this range, we recommend you test again. You may want to retest during another season of the year.
If the follow-up results are still in this range there is little short-term risk, but the decision of whether to pursue radon mitigation is a personal one, balancing costs and risks. While the United States EPA recommends action at or above the 4.0 pCi/L level, they also state:
"A radon level below 4 pCi/L still poses a risk. Consider fixing when the radon level is between 2 and 4 pCi/L."
(from Home Buyer's and Seller's Guide to Radon by US EPA)
The World Health Organization has established an action level of 2.7 pCi/L.
If you change the way you use your home, test again.
From 4.0 to 7.9 pCi/L
In this range, you should conduct either a short- or long-term follow-up measurement. If, however, this is a follow-up (confirming) test, it is recommended that you take remedial action to reduce your radon levels.
From 8.0 to 40+ pCi/L
In this range you should conduct a short-term follow-up measurement within the next few weeks, under closed house conditions. A long-term measurement is NOT recommended because exposure at these levels could pose an increased health risk.
If, however, this is a follow-up (confirming) test, it is recommended that you take remedial action to reduce your radon levels.
A list of Iowa Certified Radon Mitigators can be found at the Iowa Department of Public Health or by clicking here.