Harpreet Chohan never worried much about radon—until a close friend died of lung cancer, likely due to exposure to the radioactive gas in his home. Generated by underground uranium deposits, radon causes about 20,000 lung-cancer deaths a year, according to the U.S. Environmental Protection Agency. To help detect the invisible danger, Ecosense, the company for which Chohan works, created the EcoQube ($183), which enables users to monitor their home’s radon levels on a companion app. The small black box uses an ion chamber to detect the deadly gas, and independent tests showed that the underlying technology performs similarly to much more expensive professional radon detectors. (A device using the technology has also been certified by the National Radon Safety Board.) —Alejandro de la Garza
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