Mercury spilled from a mercurial sphygmomanometer on a hot carpet can vaporize and pollute the environment. We observed the vaporization of mercury in model experiments. Mercury (0.15g) was heated on a hot carpet and the near-by air was sampled with a midget impinger. The evaporated mercury levels were 5.0, 6.3, 8.1 and 10.0mg/m³ at 20, 40, 60 and 80 minutes, respectively at a height of 30cm from carpet. The result indicated that even if a small quantity of mercury remained on the hot carpet, it could evaporate and pollute the indoor air. Little is known about the influence on human health of low mercury exposure, especially on children. In order not to pollute the air, we need to pay attention to mercury.