What are the typical levels in DuPage County and Northern Illinois?
According to the IDNS 1990 study, the mean level of radon statewide is 2.6 Pci/L. HBIS Engineering took a sample average of its 11,000 plus tests and found our sample average to be approximately 3.5 Pci/L. The IDNS study estimates that between 25% and 50% of the buildings in DuPage County will have readings above 4.0 Pci/L. About 33% of the tests HBIS Engineering has conducted have shown to be above 4.0Pci/L. This data should be used for comparative purposes only and is not to suggest the specific level in any building or structure. According to the IDNS site map, Northern Illinois, generally has higher concentrations than Southern Illinois.
