This one page checklist, produced jointly by the CIEH and the Health Protection Agency, is designed to assist environmental health practitioners who have to conduct property inspections in identifying the possible presence of carbon monoxide. It also helps them to identify the symptoms of CO poisoning in occupants. The aim is to help EHPs deal with such incidents and reduce the harm that exposure can cause. The checklist provides practical advice on how to prevent exposure and what follow- up action to take if necessary.