Where carbon dioxide readings are between 800ppm and 1500ppm small interventions such as opening windows and doors should be adequate to bring levels below 800ppm.
Pan fydd darlleniadau carbon deuocsid rhwng 800ppm a 1500ppm, dylai ymyriadau bach fel agor ffenestri a drysau fod yn ddigon i ostwng y lefelau islaw 800ppm.