His early research in particle physics led him, as a member of the UA1 experiment, to participate in the discovery of the intermediate bosons W and Z.

[5][6][7] From 1983 to 1999, Professor Spiro lectured quantum mechanics, then stellar equilibrium and evolution and finally energy and environment at the École Polytechnique.

[10] In October 2019 Spiro was asked to replace IUPAP president Kennedy J. Reed who wanted to step down for personal reasons.

[16] Spiro chaired during 2022 and 2023 the steering committee of the International Year of Basic Sciences for Sustainable Development (IYBSSD2022).

He also contributed towards the proclamation on August 25 2023, by the United Nations General Assembly, of an International Decade of Sciences for Sustainable Development 2024 to 2033.