No. Radon has no color, odor, or taste, and it does not trip smoke or carbon monoxide alarms. Because nothing warns you, the EPA and the Ohio Department of Health both say a test is the only way to know.
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That is also why there is no list of symptoms to watch for; radon's harm shows up, if it does, as lung cancer after long exposure. Testing is cheap in Ohio. Homeowners can order a free kit through ohio.radon.com, a program the Ohio Department of Health links to and the Delaware Public Health District recommends, or buy a charcoal kit for $15 to $30. Follow Ohio's placement rules even for a do-it-yourself test: the lowest regularly used level, 20 inches to 6 feet off the floor, clear of exterior walls, doors, windows, heat sources, and the sump, and never in a kitchen, bathroom, or laundry room. The free Ohio test kit guide walks through each step.