The increasing use of recreational nitrous oxide ( \(\hbox {N}_{2}\) O) in the Netherlands and its link to traffic accidents highlights the need for reliable detection methods for law enforcement. This study focused on ex vivo detection of \(\hbox {N}_{2}\) O in exhaled breath and examining its persistence in the human body. Firstly, a low-cost portable infrared based detector was selected and validated to detect \(\hbox {N}_{2}\) O in air. Then, the influence of interferents and conditions potentially influencing the analysis were evaluated including relative humidity, ethanol, acetaldehyde and \(\hbox {CO}_{2}\) . Subsequently, \(\hbox {N}_{2}\) O breathing dynamics were evaluated in vitro and ex vivo. Initially, a lung simulator was used to model respiratory mechanics and \(\hbox {N}_{2}\) O decay, revealing detectable \(\hbox {N}_{2}\) O levels up to 90 min after exposure. In the final part of this study, a controlled single and double dose of \(\hbox {N}_{2}\) O gas was administered to 24 volunteers in an operating theatre. The presence of \(\hbox {N}_{2}\) O in exhaled breath of the volunteers was analysed using infra red spectroscopy every 12-15 min. Our results show that \(\hbox {N}_{2}\) O was detectable in exhaled breath for a minimum of 60 min post-administration and revealed a window of detection to potentially measure \(\hbox {N}_{2}\) O for law enforcement and forensic purposes.
