Plans to introduce more fresh air into Auckland’s bus fleet to reduce the risk of Covid-19 transmission were abandoned due to cost, RNZ reveals. Carbon dioxide levels inside crowded buses could be in excess of 5000 parts per million, a number which has shocked scientists. It’s more than six times the recommended safe indoor level to reduce the risk of Covid-19 transmission. Most Auckland buses do not have windows which open, and air is not drawn from outside but instead recirculated inside the bus. The buses are also not fitted with HEPA (high efficiency particulate air) air filtration, which filters virus particles.