Delays to handover patients from ambulance crews to staff in Emergency Departments (ED) have become widespread. These patients receive care within ambulances whilst waiting in designated parking bays outside ED. During this time heating, cooling, lighting and medical equipment use is often required. Although the vehicle battery can provide electrical power for limited time without running the engine, climate control and additional power is provided by running the engine, also known as idling.

In 2022, a staff Union at East of England Ambulance Service NHS Trust (EEAST) received reports from paramedics who could smell exhaust fumes whilst in the back of ambulances parked outside ED. In 2023, this Union collected reports of staff feeling unwell after spending most of their shift outside ED, with symptoms including headaches, sore throat and tiredness.

The MAPA Pilot study will test methods of measuring air pollution in preparation for a larger study examining the air pollution outside hospitals. The pilot study will be split into three workstreams, each using different methods but taking place at the same time.

Workstream 1 will use static air quality sensors mounted on the walls in an ambulance bay at Cambridge University Hospital (CUH). The device will measure carbon monoxide (CO), nitrogen dioxide (NO2) and particulate matter (PM10 and PM2.5) and record video of vehicle movements. The measurements obtained will be compared to a reference sensor, outside of the ambulance bay. Records of ambulance activity will be used to determine any association between the number of ambulances at the hospital and increased pollution levels. The sensors will be left in place for 3 months.

Workstream 2 will use smaller, handheld devices to measure air pollution inside ambulances. These devices will be placed in the cab and saloon (patient compartment) of the ambulance by designated ambulance staff on each shift. The study will collect data for one month, coinciding with the monitoring in Workstream 1.

Workstream 3 will utilise physiological measurements of CO levels in ambulance staff waiting outside the hospital study site. Pulse CO-oximetry will be used to measure physiological levels of CO in staff, as carboxyhaemoglobin (COHb). A member of research staff will visit the site regularly and offer CO-oximetry to consenting healthcare staff waiting at hospital; each staff member will complete a short health survey and record a CO measurement. Repeat measurements throughout the day will demonstrate any effects of exposure to the pollution at hospital. This will be conducted at the same time as Workstreams 1 and 2 to enable comparative data analysis.

Results from Workstreams 1 and 2 will be compared for statistical associations between external air quality and internal air quality within an ambulance. The results from Workstream 3 will be used to test whether measuring COHb is feasible in this population and generate a power calculation needed to demonstrate a link between external measurements of CO and physiological measurements of COHb.

  CO Research Circle