Abstract
In this Briefing we report on carbon dioxide (CO2) levels in public transport settings in Aotearoa NZ as a proxy measure for poor ventilation and increased Covid-19 transmission risk. In buses and trains with more than 50% of seats occupied, ventilation was typically poor 94% and 77% of the time respectively (CO2 levels above 800 ppm). These and other NZ findings (eg, from a 2022 study of Wellington’s Metlink buses) are consistent with international research also showing poor ventilation in these settings. Fortunately, there are multiple actions that transport companies and central/local government can take to improve the situation – including adopting relevant standards. Such interventions may lower the risk of Covid-19 and other respiratory virus transmission and ensure staff occupational safety.