[citation needed] When Thierry was elected to the French Parliament in June 2022, he left the presidency of the environmentalist, solidarity and citizen group of the regional council.

[3] On 26 September 2023, he announced his resignation from the group in order to comply with the internal rule of non-cumulative mandates, after a year of transition.

[5] In the National Assembly, Nicolas Thierry is a member of the Ecologist Group and sits on the Sustainable Development, Spatial and Regional Planning Committee.

[6] Thierry has an interest in Per- and polyfluoroalkyl substances, which are chemical compounds found in many manufactured products that are persistent in the environment and pose serious risks to human health.

[7] While the French government had held a report on the extent of PFAS contamination in France for several months, Thierry requested in March 2023 that it be made public.