Background and Aims: Face masks and respirators are used to filter inhaled air, which may contain airborne droplets and high particulate matter (PM) concentrations. The respirators act as a barrier to the inhaled and exhaled air, which may change the nasal airflow characteristics and air-conditioning function of the nose. This study aimed to evaluate the serum oxygen levels following the use of three-layer, five-layer and N95 masks after intervals of 1,2,3 hours in dental students of Azad University.
Materials and Methods: This cross-sectional analytical study was performed on 38 dental students of Islamic Azad University in 2020-2021. Initially, their arterial oxygen content was measured 20 minutes before the start of the study and at rest using a pulse oximeter. Then, for three days, the students put three-layer, five-layer and N95 masks on their faces, respectively, and after 1, 2 and 3 hours, their arterial oxygen level was measured by a pulse oximeter. SPSS software and one-way ANOVA, repeated measures ANOVA, Bonferroni and Tukey tests were used to analyze the data (p <0.05).
Result: After one, two and three hours wearing the mask, the highest mean percentage of serum oxygen in the blood was present in the three-layer mask, the five-layer mask and the N95 mask, respectively. The mean serum oxygen saturation percentage one hour after wearing the mask was not significantly different between the groups without mask, three-layer, 5-layer and N95 masks (p <0.05). At two and three hours, the percentage of blood serum oxygen in the groups of three-layer, 5-layer and N95 masks was significantly lower than before the study (p <0.001). At two hours, the percentage of serum oxygen in the groups of three-layer masks was significantly higher than the five-layer masks (p = 0.027) and N95 (p = 0.014). At three hours, the percentage of serum oxygen in the blood in the three-layer mask groups was similar to the five-layer and N95 masks (p <0.05). In all three types of face masks, the evaluation time had an effect on the percentage of serum oxygen saturation in the blood (p <0.05). The mean percentage of serum oxygen in the blood before the study was not significantly different from one hour after wearing the mask (p <0.05). However, the mean percentage of serum oxygen in the blood at two hours (p <0.001) and three hours (p = 0.005) after wearing the mask was significantly lower than before the start of the study. The mean percentage of serum oxygen in the blood was not significantly different between one hour and two and three hours of wearing a mask (p <0.05).
Conclusion: After two or three hours of wearing face masks, the level of serum oxygen in the blood decreased. Respiratory consequences of decreased blood oxygen saturation can be harmful. Therefore, to prevent such consequences, it is recommended to take preventive measures.