7. Associated risks and monitoring

CO ₂ occurs naturally in the atmosphere. Its volume content in homes and workplaces generally varies from 0.04 to 0.06%. Occupational exposure limit values are 5,000 ppm by volume (0.5%) at 8 h per day and 40 h per week .

Existing geological reservoirs have demonstrated their ability to hold gas and oil for millions of years. It is not uncommon for these reservoirs to contain CO ₂ . Natural CO ₂ deposits exist (example of Montmiral in the Drôme). This shows that underground reservoirs can be watertight...