Advanced Cardiothoracic Imaging Unit, Department of Imaging, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy.
Medical Direction, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy.
Int J Environ Res Public Health. 2022 Mar 14;19(6):3435. doi: 10.3390/ijerph19063435.
Our goal is to evaluate the effects of heat and ultraviolet (UV) irradiation on P3 facial respirator microstructure.
P3 facial filters were exposed to dry heat and UV sterilization procedures.
P3 facial filter samples underwent a standardized sterilization process based on dry heat and UV irradiation techniques. We analyzed critical parameters of internal microstructure, such as fiber thickness and porosity, before and after sterilization, using 3D data obtained with synchrotron radiation-based X-ray computed microtomography (micro-CT). The analyzed filter has two inner layers called the "finer" and "coarser" layers. The "finer" layer consists of a dense fiber network, while the "coarser" layer has a less compact fiber network.
Analysis of 3D images showed no statistically significant differences between the P3 filter of the controls and the dry heat/UV sterilized samples. In particular, averages fiber thickness in the finer layer of the control and the 60° dry heated and UV-irradiated sample groups was almost identical. Average fiber thickness for the coarser layer of the control and the 60° dry heated and UV-irradiated sample groups was very similar, measuring 19.33 µm (±0.47), 18.33 µm (±0.47), and 18.66 µm (±0.47), respectively. There was no substantial difference in maximum fiber thickness in the finer layers and coarser layers. For the control group samples, maximum thickness was on average 11.43 µm (±1.24) in the finer layer and 59.33 µm (±6.79) in the coarser layer. Similarly, the 60° dry heated group samples were thickened 12.2 µm (±0.21) in the finer layer and 57.33 µm (±1.24) in the coarser layer, while for the UV-irradiated group, the mean max thickness was 12.23 µm (±0.90) in the finer layer and 58.00 µm (±6.68) in the coarser layer. Theoretical porosity analysis resulted in 74% and 88% for the finer and coarser layers. The finer layers' theoretical porosity tended to decrease in dry heat and UV-irradiated samples compared with the respective control samples.
Dry heat and UV sterilization processes do not substantially alter the morphometry of the P3 filter samples' internal microstructure, as studied with micro-CT. The current study suggests that safe P3 filter facepiece reusability is theoretically feasible and should be further investigated.
评估热和紫外线（UV）辐照对 P3 面部呼吸器微观结构的影响。
P3 面部过滤器经过干热和 UV 消毒程序处理。
P3 面部过滤器样本经过基于干热和 UV 辐照技术的标准化消毒过程。我们使用基于同步加速器辐射的 X 射线计算微断层扫描（微 CT）获得的 3D 数据，分析内部微观结构的关键参数，如纤维厚度和孔隙率，在消毒前后。分析的过滤器有两个内层，称为“较细”和“较粗”层。“较细”层由致密的纤维网络组成，而“较粗”层的纤维网络不太紧密。
3D 图像分析显示，对照组和干热/UV 消毒样品之间的 P3 过滤器没有统计学上的显著差异。特别是，对照组和 60°C 干热及 UV 照射组的较细层平均纤维厚度几乎相同。对照组和 60°C 干热及 UV 照射组的较粗层平均纤维厚度非常相似，分别为 19.33 µm（±0.47）、18.33 µm（±0.47）和 18.66 µm（±0.47）。较细层和较粗层的最大纤维厚度没有明显差异。对于对照组样品，较细层的最大厚度平均为 11.43 µm（±1.24），较粗层为 59.33 µm（±6.79）。类似地，60°C 干热组样品在较细层中增厚 12.2 µm（±0.21），在较粗层中增厚 57.33 µm（±1.24），而对于 UV 照射组，平均最大厚度为 12.23 µm（±0.90）在较细层和 58.00 µm（±6.68）在较粗层。理论孔隙度分析得出，较细层和较粗层分别为 74%和 88%。与相应的对照样品相比，干热和 UV 照射样品中较细层的理论孔隙度有减小的趋势。
微 CT 研究表明，干热和 UV 消毒过程不会显著改变 P3 过滤器样品内部微观结构的形态计量学。本研究表明，P3 过滤器面罩的安全重复使用在理论上是可行的，应该进一步研究。
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