Alexander Klementiev was born in Moscow in 1942 and grew up in the Soviet Union during the Cold War. As a student, he attended the Moscow Institute of Physics and Technology, where he studied radio physics and earned his Ph.D.
He also served as a research fellow for the International Institute for Applied Systems Analysis in Vienna, Austria. He later worked on projects to analyze the morality of individuals who lived in areas contaminated by the Chernobyl reactor accident. In 1985, his book Years of Quantitative Modeling for Solving Public Health Problems was published.
In 1992, Klementiev immigrated to the United States. He then began to work with attorney Tom Foulds. He worked on estimating radioactive releases from the Hanford Site facilities and the lifetime risk of radiation-induced thyroid disease for the Hanford downwinders. Since 1996, Klementiev has worked for the Health Department in Pierce County, Washington, as an epidemiologist responsible for public health evaluation.