Household humidifiers can inadvertently release contaminants to the atmosphere with water. Four types of humidifiers were tested to estimate the release rate of elements from the water. Stable nickel, selenium, iodine, and uranium tracers were used as analogues of some important radionuclides in the assessment of the disposal of used nuclear fuel. Humidifiers that inject water droplets into the air were the most efficient at releasing the elements from the water. Calculations of potential radiological dose to humans indicate that doses are less than 0.2 mSv y-1 if water was contaminated up to the maximum regulatory levels for several radionuclides.