The High Council for Public Health (HCSP)’s statement on the measurement of carbon dioxide (CO2) is part of the evolution of the regulatory framework for mandatory monitoring of indoor air quality in certain public access buildings (PAB), at key moments in the life of the buildings, according to action n°14 of the National Health and Environment Plan 2021-2025 (PNSE4).

The rise in concentrations of CO2, a molecule produced by human respiration, corresponds to a confinement of the air in premises which is associated with a decrease in cognitive performance and, in the presence of source persons, an increase in the concentration of airborne infectious agents.

The HCSP defines for the PAB :

• a management benchmark value for a concentration of 800 ppm CO2 as a target for satisfactory air renewal in occupied premises, through the supply of fresh air;
• a rapid action value for a concentration of 1500 ppm, indicating air confinement that is not acceptable according to the scientific literature and requiring corrective action.

The HCSP recommends that ventilation strategies and the occupancy gauge for closed spaces in public buildings should be dimensioned by continuously recording CO2 concentrations over a one-week occupancy period in order to calculate a confinement index (ICONE) during building works, including energy renovation works.

The HCSP recommends the use of CO2 detectors during periods of occupancy in different categories of establishments, in order to ensure real-time air renewal conditions when there are changes in occupancy levels and/or activity in the premises.