Studies in other states have found similar levels of poor air quality in classrooms. Elevated CO₂ concentrations can cause headache, drowsiness and lethargy. Children under 15 are particularly vulnerable to poor air quality. Pollutant exposure during developmental stages may produce lifelong issues such as respiratory infections. Australian students spend at least 25 hours in classrooms per week, or in excess of 1,075 hours indoors, in school buildings, annually. Australia’s National Construction Code (NCC) specifies CO₂ concentration levels of less than 850 parts per million (ppm), averaged over eight hours, for acceptable air quality. In our analysis, the CO₂ concentrations in Victorian classrooms ranged from 912 to 2,235 ppm. During certain times of occupied hours, levels reached up to 5,000 ppm.