The quality of indoor air can greatly influence our health, wellbeing, and comfort. Central to this is the presence of carbon dioxide, often abbreviated as CO2. While CO2 is a typically harmless gas that exists virtually everywhere, high CO2 levels indoors can pose various health risks. Hence there’s an increasing need for homeowners to understand CO2 levels inside their homes and their implications on health.
What is CO2 and what are its sources indoors?
CO2, or carbon dioxide, is a colorless, odorless gas. It’s a normal component of air and serves essential roles in various ecosystems. In photosynthesis, plants use CO2 and sunlight to make food and release oxygen. In humans and animals, it’s a waste product of respiration; we inhale oxygen and exhale CO2.
In indoor environments, the most common sources of CO2 include humans, pets, combustion processes (including cooking and burning candles), and indoor plants during night hours (since photosynthesis halts). The concentration of CO2 increases with the number of people in the space, their rates of respiration, how long they stay, and the ventilation quality.
Understanding and measuring CO2 levels indoors
CO2 levels in indoor environments are often used as an indicator of indoor air quality, primarily tied to ventilation efficiency. The level of CO2 indoors can vary, often depending on the factors mentioned above. However, certain averages and thresholds provide useful guidelines.
Typical background levels of CO2 in external air are approximately 400 parts per million (ppm). In indoor spaces, levels below 1,000 ppm are generally satisfactory, suggesting efficient ventilation. Levels between 1,000–2,500 ppm indicate inadequate ventilation, while anything above 2,500 ppm can potentially cause discomfort and possible health effects. It’s recommended that sample measurements are taken over time to account for variations in CO2 levels.
Health effects of high CO2 levels indoors
While most scenarios of CO2 exposure are harmless, high levels can pose health risks. Below is a discussion of what could occur at various concentrations:
1) 1,000-2,000 ppm: At these levels, you might start to feel air deprivation. While these concentrations don’t pose any significant health threat, they could cause discomfort and subtly reduce cognitive function.
2) 2,000-5,000 ppm: Continued exposure to these levels often leads to symptoms such as headaches, sleepiness, poor concentration, loss of attention, increased heart rate, and slight nausea.
3) Over 5,000 ppm: This concentration can cause marked hyperventilation and headaches in short exposure. Long-term exposure at these levels can lead to more severe symptoms such as shortness of breath, trembling, and an increased likelihood of irreversible effects.
4) Over 40,000 ppm: Direct exposure to such high concentrations can be life-threatening, leading to severe oxygen deprivation in the nervous system and potentially heart failure.
Managing CO2 levels in your home
Ensuring your home has low CO2 levels primarily involves efficient ventilation and awareness of activities that increase CO2 concentration. Here are some ways you can manage CO2 levels:
1) Ventilation: Regularly airing your rooms, doing simple things like opening your windows, or using extraction fans can greatly reduce CO2 levels. Mechanical ventilation systems are also a worthy investment.
2) CO2 monitors: Installing these can help you keep track of CO2 levels in real-time while alerting you of undesirably high levels.
3) Reduce human concentration: This means avoiding overcrowding in indoor spaces, which directly increases CO2 levels due to human respiration.
4) Limit combustion activities: Combustion activities such as cooking or burning candles significantly increase CO2 emission. Make sure they’re done with proper ventilation.
5) Indoor plants: Indoor plants consume CO2 and release oxygen during the day, aiding in CO2 reduction. However, remember they reverse this process at night.
6) Energy Recovery Ventilators (ERVs): ERVs exchange stale indoor air with fresh outdoor air, reducing indoor CO2 levels.
Today’s growing focus on energy efficiency and ‘airtight’ homes can cause CO2 build-up. Hence, the understanding and monitoring of indoor CO2 levels have become more critical. As well as being mindful of building materials and furnishings that emit volatile organic compounds (VOCs), owners and residents need to be conscious of the less visible but equally significant CO2 issue. Accurate and timely CO2 measurement can go a long way in ensuring a healthier, safer living environment.
