Do you know the maximum CO2 level in a room before it becomes a health concern? Outside, the air contains between 400 and 600 ppm (parts per million) of CO2, while indoors, concentrations can rise rapidly without you even realizing it.
According to experts, the critical threshold is 1000 ppm, beyond which air quality is considered poor. The French High Council for Public Health even recommends not exceeding 800 ppm to protect against Covid and winter infection epidemics. To effectively monitor these levels, CO2 is measured using specific sensors that precisely indicate the concentration of CO2 in ppm. According to ANSES recommendations, CO2 levels should not exceed 1000 to 1500 ppm. This article explains why these limits are important, how to detect excessively high levels of CO2 in the air, and what solutions you can implement to maintain a healthy environment.
Why is high CO2 a problem?
High CO2 levels in a room are not only uncomfortable, they also present real risks to your health. When CO2 levels exceed 1000 ppm, your cognitive abilities begin to decline significantly. In fact, a Harvard University study showed that high CO2 levels can reduce cognitive performance by up to 50%.
The first symptoms generally appear around 1000 ppm, with a feeling of discomfort and a drop in productivity. As concentration increases, you may experience headaches, fatigue, dizziness and nausea. Concentration difficulties and drowsiness gradually set in.
Above 1300 ppm, according to departmental health regulations, the effects become more marked, with possible sleep-inducing phases.
CO2 levels are a very good indicator of room containment. By maintaining an optimum CO2 level of 800-1000 ppm, you're doing everything you can to avoid the accumulation of other chemical and biological pollutants, and their effects on health.
How do I know if the CO2 level is too high?
The most reliable way to detect high CO2 levels in your environment is to use a specific sensor. Outside, CO2 concentrations range from 400 to 600 ppm, serving as a benchmark for assessing indoor air quality.
- Green: 800 ppm - Excellent air quality
- Yellow/Orange: 800 to 1500 ppm - Average air quality, aeration recommended
- Red: over 1500 ppm - Poor air quality, ventilation imperative
However, some more precise devices refine these thresholds: green up to 800 ppm, yellow from 800 to 1200 ppm, orange from 1200 to 1500 ppm, and red above that. The Haut Conseil de la Santé Publique (French High Council for Public Health) recommends not exceeding 800 ppm, particularly during epidemic periods, while the Réglements Sanitaires Départementaux (French Departmental Health Regulations) set a threshold of 1300 ppm.
Remember that sensitivity to high concentrations of CO2 varies from one individual to another.
How to stay under the limit?
Keeping CO2 levels below recommended thresholds requires concrete, regular action. Fresh-air ventilation remains the most controlled and effective solution for reducing CO2 levels. In the absence of a mechanical ventilation system, a strategy of natural ventilation through the windows can be implemented. Open your windows for 15 to 20 minutes every day, several times a day. For optimum efficiency, create air currents by opening several windows simultaneously on opposite sides of the building, and avoid ventilating during periods of high outdoor pollution.
Controlled mechanical ventilation (CMV) is a sustainable solution. Mandatory since 1982 in new-build homes, this system ensures constant renewal of indoor air. CO2-sensor-controlled CMVs are particularly efficient, as they ventilate only when necessary, enabling energy savings of up to 40%.
Installing a CO2 detector turns air quality management into an objective process. These compact devices display concentrations in real time via colored lights: green (normal level), orange (high concentration), red (critical threshold). Position them in the busiest rooms, away from heat sources or draughts.
Don't forget to maintain your equipment on a regular basis: clean ventilation grilles monthly and replace filters according to the manufacturer's recommendations.
Conclusion
The level of CO2 in your indoor spaces therefore plays a fundamental role in your daily health and well-being. Of course, keeping this level below 800-1000 ppm is a challenge, especially for rooms with high occupancy rates (classrooms, nurseries, etc.) and no mechanical ventilation.
Installing a CO2 detector is undoubtedly the wisest investment you can make to effectively monitor your air quality. This small device will alert you before the first symptoms appear.
Your vigilance with regard to CO2 levels becomes all the more important during epidemic periods, when well-renewed air considerably limits the spread of micro-organisms. Vulnerable people, especially those suffering from asthma or respiratory disorders, will also benefit from increased attention to this issue.
After all, indoor air quality deserves the same attention as your diet or sleep. A healthy environment, with controlled CO2 levels, guarantees not only better long-term health, but also more productive days and much greater comfort in everyday life.
FAQs
Q1. What is the recommended CO2 level in a room?
The recommended CO2 level should not exceed 800 ppm, according to the French High Council for Public Health. Above 1000 ppm, air renewal is considered insufficient and can affect health and cognitive performance.
Q2. How can I detect high CO2 levels in my home?
Using a CO2 sensor is the most reliable way. These devices generally use a color code: green for excellent air quality (0-<800 ppm), yellow/orange for average quality (800-1500 ppm), and red for poor quality (over 1500 ppm).
Q3. What are the health effects of high CO2 levels?
High CO2 levels can cause headaches, fatigue, concentration difficulties and reduced productivity.
Q4. What are the best solutions for reducing CO2 levels in a room?
Installing a controlled mechanical ventilation system (CMV) to blow fresh air into the room is the most effective and controlled solution for guaranteeing good air renewal over time. Natural ventilation by opening windows for 15 to 20 minutes a day is recommended in the absence of mechanical ventilation. In addition, the use of CO2 sensors to monitor levels is also recommended in order to fine-tune the natural ventilation strategy implemented.
Q5. Does CO2 have an impact on the spread of viruses?
CO2 levels are an indicator of room confinement. High CO2 levels mean that air renewal is poor and biological pollutants can accumulate. That's why it's particularly important to keep the level low, especially during epidemic periods. The French High Council for Public Health recommends not exceeding 800 ppm to protect against Covid.
