Photochemical Degradation of Some Halogenated Anesthetics in Air

Anesthetic gases enter the environment primarily through patient exhalation and venting from scavenging systems directly into the atmosphere. Emissions of halogenated anesthetic gases like halothane, isoflurane and sevoflurane are of concern due to their high global warming potential, highlighting the need to mitigate their environmental impact. Photocatalytic oxidation has been proposed as a potential option for emission control and indoor air treatment, but data on its use for various halogenated anesthetics is very limited. In this work, photocatalytic oxidation efficiency for the degradation of halothane was studied by varying the method for catalyst support and catalyst mass loading. Approximately 99.9% of halothane (1296 mg/m3) in air was degraded with a TiO2 photocatalyst under UVC light (254 nm) in 35 min in a recirculating batch photoreactor. The optimized conditions for halothane demonstrated a similar although faster photocatalytic degradation efficiency for isoflurane (99.8% in 20 min, 911 mg/m3) and sevoflurane (>98% in 10 min, 847 mg/m3). The results presented here suggest that a UV–photocatalysis is a promising technique to treat such anesthetic gases before being released into the environment by scavenging systems, although significant work remains to identify the potential by-products and optimal photoreactor designs for efficient long-term operation.