When we think of carbon dioxide levels, most of us think of burning fossil fuels or climate change, yet, elevated indoor levels of carbon dioxide are also concerning due to the effects on the human brain and overall health. Unfortunately, many schools, cars, gyms, offices, meeting rooms, and bedrooms have concerning levels of carbon dioxide that impact our cognitive and decision-making abilities.
Carbon dioxide is a colorless, odorless gas that is created from metabolic activity. People and animals exhale carbon dioxide. Thus, overcrowded spaces without ventilation can contain very high levels. Carbon dioxide is also plentiful in the atmosphere, and typical outdoor levels are around 400 ppm. Levels often rise in occupied, confined spaces and are related to tight constructions without ample ventilation. High carbon dioxide levels can also be an indication that other indoor pollutant levels are also elevated because it indicates that a building is not properly ventilated.
The Effects of CO2 on the Brain
Closed, poorly ventilated spaces often have carbon dioxide levels greater than 1000 parts per million. Headaches, impaired mental function, lethargy, and even reduced school attendance have all been linked to high carbon dioxide concentrations that many people are exposed to in their daily lives for hours at a time.
A study of working professionals (Allen et al. 2015) found diminished workplace performance by working professionals, with a 15 and 50 percent reduction in decision-making performance at 945 ppm and 1,400 ppm, over the 550 ppm control group. Cognitive function decreased by an average of 21 percent with a 400 ppm increase in carbon dioxide. Such a significant reduction in workplace performance can also impact profitability, thus impacting the bottom line for businesses. Unfortunately, many schools, building managers, landlords, and homeowners are unaware of this issue and therefore don’t take corrective action to improve indoor air quality.
High Indoor Levels of Carbon Dioxide
Unventilated bedrooms often have high concentrations of carbon dioxide, especially when there is more than one occupant using the room. Typically, carbon dioxide levels rise during the night when people are sleeping, especially if the door and windows are closed. The concentrations then fall during the day if the room is unoccupied. Unfortunately, poor air quality can hinder restful sleep and optimum health in many homes.
Studies also show that classrooms and offices often have elevated carbon dioxide levels that sometimes exceed 2,000 or even 3,000 ppm. Prolonged exposure, especially in unventilated spaces, is especially concerning given that high cognitive function is especially important in school and workplace settings.
Fresh Air Solutions
Elevated carbon dioxide concentrations are an indication that there isn’t enough fresh air in many buildings and homes. Tight construction allows less air to exchange between the inside and the outside, requiring mechanical ventilation.
When possible, opening windows and doors can help dilute indoor pollutants. Exhaust fans in bathrooms and range hoods in kitchens are helpful for removing moisture, odors, and particles but do not necessarily lower carbon dioxide concentrations elsewhere. In addition, exhaust fans are often ineffective in tightly constructed spaces because makeup air is needed to replace the exhausted air. Balanced ventilation solutions are a good option in tightly constructed homes and buildings because they both exhaust carbon dioxide and supply fresh air, allowing air to exchange between the inside and outside of the building.
Zehnder ComfoAir Ventilators
Zehnder heat recovery ventilators supply a constant stream of fresh air to bedrooms, offices, gyms, and schools while simultaneously exhausting stale, contaminated air. These heat recovery ventilation systems are up to 95 percent efficient in transferring heat from the exhaust air to the intake air, saving energy. Projects retrofitted with Zehnder systems have shown a significant increase in indoor air quality, including reduced carbon dioxide, formaldehyde, microbial volatile organic compounds, and total volatile organic compound (VOC) levels.
As the concept of achieving optimum health and productivity grows in popularity, indoor air quality is also gaining more attention. Reducing airborne contaminants from the air is an important way to improve cognitive function, alertness, and overall energy levels.