Topic: Carbon Dioxide (CO2)
During the month of April, the average daily carbon dioxide (CO2) levels fluctuated between 500 and 650 parts per million (ppm) in over 300 office buildings in Switzerland and Germany. This is much lower than the short-term threshold of 1000 ppm (based on a 24-hour mean) established by the Directorate of Labor and Working Conditions at Swiss State Secretariat for Economic Affairs (SECO), suggesting that clients are either using appropriate ventilation practices and/or efficiently utilizing the available workspace in the monitored areas.
1. General Description and Health Effects
Indoor CO2 levels are an important aspect to consider for the overall health and well-being of individuals who spend extended periods indoors. Carbon dioxide is a naturally occurring gas that is a byproduct of human respiration and combustion processes. While it is not toxic at low concentrations, prolonged exposure to elevated levels of CO2 can have negative health effects. High CO2 levels can cause headaches, fatigue, dizziness, and difficulty concentrating. Additionally, it may exacerbate respiratory conditions, such as asthma, and cause eye and throat irritation.
Studies have shown that high CO2 concentrations in indoor environments can also influence cognitive function. Specifically, it can impair decision-making, decrease productivity, and increase absenteeism. It is essential to maintain indoor CO2 levels at a healthy range to ensure the health and comfort of building occupants. The Directorate of Labor and Working Conditions at Swiss State Secretariat for Economic Affairs (SECO) recommends indoor CO2 levels should not exceed 1000 parts per million (ppm). In addition, adequate ventilation and air exchange systems should be implemented to ensure optimal indoor air quality.
2. Sources and Pathways of Exposure
The primary source of indoor CO2 is human respiration, with their strong correlation demonstrated on the measurement plots (i.e., human-driven CO2 volatility). Besides, other sources like poor ventilation, overcrowding, and the use of gas stoves and heaters may contribute to elevated indoor CO2 levels. Pathways of exposure to high CO2 levels include inhalation of air contaminated with elevated levels of CO2 and direct contact with skin or eyes. It is important to identify potential sources of elevated CO2 levels and take measures to mitigate them to ensure healthy indoor air quality. Regular air quality testing can help identify sources and allow corrective actions to be taken.
3. Factors Influencing CO2 levels Indoors
Several factors can influence indoor CO2 levels. The number of occupants in a building, their activity level, the size of the space, and ventilation practices can all influence the concentration of CO2. For example, a small room with several people will experience a more rapid buildup of CO2 than a larger space with the same number of occupants. Additionally, factors such as ventilation rates, building design, and the use of energy-efficient materials can influence indoor CO2 levels. Adequate ventilation and air exchange systems can help maintain healthy indoor CO2 levels. Building design elements such as the use of operable windows, natural ventilation, and building orientation can also play a significant role in reducing CO2 buildup indoors. Regular maintenance of HVAC systems, including cleaning and replacing air filters can also help ensure optimal indoor air quality.
4. Measures to Mitigate High CO2 Level Indoors
The first step is to identify potential sources of elevated CO2 levels and take corrective actions. This may include increasing ventilation rates by opening windows, installing air exchange systems, or adjusting HVAC systems. It is also important to limit the number of occupants in a space and promote proper ventilation using fans or air purifiers. For workplaces with natural ventilation via operable windows, short and intensive ventilation is most effective (e.g. open all windows for 5 to 10 minutes every 1 to 2 hours).
Additionally, a green or living wall can be installed to help remove CO2 from the air while providing aesthetic benefits. Indoor plants are another effective solution, as they absorb CO2 and other harmful chemicals. Regular air quality monitor and testing can also help identify potential issues and ensure that mitigation measures are effective.
Written by Dr. Erfan Haghighi, Head of R&PD