danger of radioactive contamination from radon gas - concept with warning of radioactivity on road sign

radon alert signal attention caution warning sign contaminant hazard indoor air quality symbols gas graph chart checkup test results examining check up trend radioactive contamination radioactivity dangerous area precaution symbol toxic danger nuclear energy water pollution lung cancer radiation waste polluted risk poisonous security safe safety concepts copy space uranium poison triangle shape environment ionizing environmental conservation road issues substance intoxication damage atomic atom