Acceptable Lifetime CO2 Exposure Limit for Humans

Determine an acceptable lifetime exposure limit for human exposure to atmospheric carbon dioxide, or ascertain whether such a limit exists.

Background

The paper reviews evidence that elevated atmospheric CO2 affects human physiology and cognition, noting that while very high concentrations are known to be lethal and short-term occupational limits exist, effects at lower, chronic exposures remain insufficiently characterized. It highlights studies reporting measurable cognitive and metabolic impacts at concentrations between 600–1000 ppm, while acknowledging critiques and inconsistencies in the literature.

Given that modern lifestyles involve prolonged time indoors where CO2 often exceeds outdoor levels and that atmospheric CO2 continues to rise, the authors stress that a scientifically grounded lifetime exposure limit has not been established and may or may not exist, framing a critical public health knowledge gap.