Carbon Dioxide (CO2)

What is CO2?
Carbon dioxide (CO2) is a naturally occurring gas in Earth's atmosphere, essential for life. It is a byproduct of cellular respiration in humans and animals, used by plants in photosynthesis, and a key greenhouse gas influencing climate. While normal atmospheric levels are around 0.04% (400 ppm), human activities, such as fossil fuel combustion, have significantly increased concentrations, contributing to global warming.

Direct Health Effects of CO2 Exposure

1. ​Normal Levels (400–1,000 ppm): No immediate health effects, but levels above 1,000 ppm in poorly ventilated spaces may cause drowsiness, reduced concentration, and discomfort.
2. ​Moderate Exposure (1,000–5,000 ppm): Symptoms include headaches, dizziness, increased heart rate, and shortness of breath. Cognitive performance can decline at ~1,000 ppm.
3. ​High Exposure (>5,000 ppm): OSHA's 8-hour exposure limit is 5,000 ppm. Levels above this can lead to hypercapnia (excessive blood CO2), causing respiratory acidosis, confusion, and asphyxiation due to oxygen displacement.
4. ​Extreme Levels (>10% concentration): Rapid unconsciousness, convulsions, and death within minutes due to oxygen deprivation.

Indirect Health Impacts

• ​Climate Change: CO2-driven global warming exacerbates extreme weather (heatwaves, storms), spreads vector-borne diseases, and worsens air quality (e.g., ground-level ozone), aggravating respiratory conditions like asthma.
• ​Ocean Acidification: CO2 dissolving in oceans forms carbonic acid, threatening marine ecosystems and fisheries, impacting food security and livelihoods.
• ​Indoor Air Quality: Elevated CO2 often signals poor ventilation, correlating with accumulation of pollutants (VOCs, allergens) that affect respiratory health.

Contextual Considerations

• ​Industrial/Confined Spaces: Risks in breweries, dry ice usage, or poorly ventilated areas require monitoring to prevent dangerous CO2 buildup.
• ​Medical Uses: Controlled CO2 applications, such as in surgery or therapies, are safe under professional supervision.

Conclusion
While CO2 is non-toxic at normal levels, elevated concentrations pose direct health risks, primarily through oxygen displacement and acid-base imbalances. Indirectly, its role in climate change and ocean acidification underscores broader public health challenges. Ensuring proper ventilation and mitigating emissions are critical to minimizing adverse effects.