Radon is a radioactive element that is an inert or chemically inactive gas produced by decay of natural radium. Radon is odorless, invisible, and tasteless, and moderately soluble in water. Radium, which produces radon, is the decay product of thorium and uranium found in rock and soil. Uranium-238 decays to radium-226 which decays into radon-222, which is a known human carcinogen. Prolonged exposure to elevated radon concentrations causes an increased risk of lung cancer. Like other environmental pollutants, there is some uncertainty about the magnitude of health risks attributed to radon exposure. The Environmental Protection Agency (EPA) estimates that radon may cause about 14,000 lung cancer deaths in the U.S. each year. However, this number could range from 7,000 to 30,000 deaths per year. The U.S. Surgeon General has warned that radon is the second-leading cause of lung cancer deaths.

Radon Surveys have become an important aspect in real estate sales and purchases. In many states, radon disclosure is required before a real estate transaction can be completed. EI maintains a staff of professionals certified by the EPA's Radon Measurement Proficiency (RMP) Program. In addition, EI is listed with the EPA for secondary measurement services and has been issued RMP number 2214600.