The National Collaborating Centre for Environmental Health produces case studies of real life scenarios to assess and offer solutions to potential environmental health issues. One case study created addressed high levels of carbon dioxide in an older school facility in Canada. Here are the key findings.
Average indoor co2 levels
As the natural product of human breathing, carbon dioxide is a natural component of air. It is colourless and odourless, meaning it is difficult to detect without monitoring equipment. Outdoor air contains a concentration of carbon dioxide between 300 and 400 ppm. Indoor air typically has higher concentrations of carbon dioxide – humans can cause concentrations in indoor to rise above 3,000 ppm from just normal breathing.
Human health effects begin at around 7,000 ppm. The exposure limit set by Health Canada is 3,500 ppm.
the solution is ventilation
Carbon dioxide in indoor air is unavoidable. Humans need to breath and indoor combustion (such as furnaces and gas stoves) can contribute to higher concentrations. Besides optimizing equipment for more complete combustion, it is difficult to cut off the source of carbon dioxide.
The solution is ensuring buildings have sufficient ventilation.
Carbon dioxide standards for indoor air
A measure of adequate ventilation is monitoring the concentrations of carbon dioxide. The ASHRAE standards for indoor air quality recommend carbon dioxide levels between 1,000 to 1,100 ppm. Improvements in ventilation are recommended if average concentrations rise above 1,100 ppm.
Going beyond carbon dioxide
Carbon dioxide is only one component of indoor air. Volatile organic compounds, mould, carbon monoxide and radon are other potential components of air that can have a negative impact on human health. Fortunately, adequate ventilation is a major factor to improving indoor air quality for all potential hazards.
Read the entire case study by the National Collaborating Centre for Environmental Health.