Radon Ventilation Systems Design Radon is a naturally occurring radioactive gas . It is colorless, odorless, and tasteless, making it difficult to detect without specialized equipment. Radon forms as a byproduct of the decay of uranium in soil, rock, and water. Because it is a gas at room temperature, radon can seep through the ground and enter homes, especially through cracks in the foundation, and accumulate to dangerous levels in poorly ventilated areas. It is not a liquid