Department of Urology, University of Washington, Seattle Children's Hospital, Seattle, WA.
Department of Materials Science and Engineering, Stanford University, Stanford, CA.
Am J Infect Control. 2022 Aug;50(8):857-862. doi: 10.1016/j.ajic.2022.03.003.
Global shortage of personal protective equipment (PPE), as consequence of the COVID-19 global pandemic, has unmasked significant resource inequities prompting efforts to develop methods for safe PPE decontamination for reuse. The World Health Organization (WHO) in their Rational Use of PPE bulletin cited the use of a photodynamic dye, methylene blue, and light exposure as a viable option for N95 respirator decontamination. Because WHO noted that methylene blue (MB) would be applied to surfaces through which health care workers breathe, we hypothesized that little to no MB will be detectable by spectroscopy when the PPE is subjected to MB at supraphysiologic airflow rates.
A panel of N95 respirators, medical masks, and cloth masks were sprayed with 5 cycles of 1,000 uM MB solution. Mask coupons were subjected to the equivalent of 120 L/min of 100% humidified air flow. Effluent gas was trapped in an aqueous solution and the resultant fluid was sampled for MB absorbance with a level of detection of 0.004 mg/m3.
No detectable MB was identified for any mask using Ultraviolet-Visible spectroscopy.
At 500-fold the amount of MB applied to N95 respirators and medical masks as were used for the decontamination study cited in the WHO Rational Use of PPE bulletin, no detectable MB was observed, thus providing safety evidence for the use of methylene blue and light exposure for mask decontamination.
由于 COVID-19 大流行，全球个人防护设备（PPE）短缺，暴露出了重大的资源不平等问题，促使人们努力开发安全的 PPE 消毒再利用方法。世界卫生组织（WHO）在其《PPE 的合理使用》公告中引用了使用光动力染料亚甲蓝（MB）和光照作为 N95 呼吸器消毒的可行选择。由于 WHO 指出 MB 将通过医护人员呼吸的表面进行应用，我们假设当 PPE 受到高于生理气流率的 MB 处理时，通过光谱法几乎无法检测到 PPE 中的 MB。
一组 N95 呼吸器、医用口罩和布口罩用 5 个周期的 1000 μM MB 溶液喷雾处理。口罩样品接受相当于 120 L/min、100%加湿空气流量的处理。废气被捕获在水溶液中，并用紫外-可见光谱法对所得液体中的 MB 吸收度进行采样，检测限为 0.004 mg/m3。
使用紫外-可见光谱法未检测到任何口罩上的 MB。
在 WHO《PPE 的合理使用》公告中提到的用于消毒研究的 N95 呼吸器和医用口罩的 MB 用量增加了 500 倍，但未观察到可检测到的 MB，因此为使用亚甲蓝和光照进行口罩消毒提供了安全证据。
