Wikipedia defines Radio Frequency Interference as:
“Electromagnetic interference (or EMI, also called radio-frequency interference or RFI when in high frequency or radio frequency) is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. These effects can range from a simple degradation of data to a total loss of data.”
This article discusses RFI and breath testing machines.