The first step in mitigation is testing to see if the indoor-air and/or domestic water radon concentrations should be reduced. No level of radiation is considered completely safe, but it cannot be totally eliminated so governments around the world have set various "action levels" to provide guidance on when radon concentrations should be reduced. The World Health Organization's International Radon Project has recommended an action level of 100 Bq/m3 (2.7 pCi/l) for radon in the air. Radon in the air is considered to be a larger health threat than radon in domestic water so the US Environmental Protection Agency recommendation is to not test for radon in water unless a radon in air test is above the action level. However, some US states, such as Maine where radon levels are higher than the national average, recommend all well water should be tested for radon. The US government has not set an action level for radon in water.