A new study published in the New Zealand Medical Journal measured nighttime carbon dioxide levels in 20 Wellington homes. Researchers found CO2 concentrations exceeded the 800ppm target in most bedrooms, with half peaking above 2000ppm and one reaching over 8000ppm. Higher CO2 levels were linked to worse sleep quality, reduced next-day performance, and increased risk of mold and respiratory issues. Newer, more airtight homes had worse CO2 buildup than older leakier houses. The study points to a gap in building codes, which lack ventilation requirements for bedrooms. Researchers recommend opening windows or doors at night and ensuring vents are clear, but note that mechanical ventilation systems may be needed despite their cost. The findings suggest this may be an under-recognized public health issue across New Zealand. Improving home ventilation could improve health outcomes and energy efficiency, with implications for building standards and retrofit programs.
