Emergency Departments are often the first opportunity for diagnosis of carbon monoxide poisoning.

In 2015 the Department of Health estimated that around 4,000 people attending Accident and Emergency departments each year in the UK are diagnosed with carbon monoxide poisoning.
You can read more about the Department of Health study.
When we begin to experience winter temperatures, home heating systems get switched on, often for the first time in 6 months. The risk of carbon monoxide poisoning increases, and emergency departments begin to see an increase in cases.
However, accurate numbers are difficult to determine because the signs and symptoms of carbon monoxide poisoning are very similar to other common illnesses and are easily misdiagnosed.
This is exacerbated by the fact that the heating season coincides with flu season.

A research project carried out by St George’s, Epsom and St Helier University Hospitals, University of Surrey and Frimley Health Foundation Trust has sought to reduce misdiagnosis so that patients can be treated appropriately and not sent back to the site of exposure before it is safe to do so.

You can read more about this study here.
Below Professor Heather Jarman speaks about the challenges faced by clinicians when faced with a possible carbon monoxide poisoning diagnosis.