BACKGROUND: SARS-CoV-2 (COVID-19) is transmitted via infectious respiratory particles. Infectious respiratory particles are released when an infected person breathes, coughs, or speaks. Several studies have measured respiratory particle concentrations through focusing on activities such as breathing, coughing, and short speech. However, few studies have investigated the effect of speech duration. METHODS: This study aimed to clarify the effects of speech duration and volume on the respiratory particle concentration. Study participants were requested to speak at three voice volumes across five speech durations, generating 15 speech patterns. Participants spoke inside a clean booth where particle concentrations and voice volumes were measured and analyzed during speech. RESULTS: Our findings suggest that as speech duration increased, the aerosol number concentration also increased. Through focusing on individual differences, we considered there might be super-emitters who emit more aerosol particles than the average human. Two participants were identified as statistical outliers (aerosol number concentration, n = 1; mass concentration, n = 1). CONCLUSIONS Considering speech duration may improve our understanding of respiratory particle concentration dynamics. Two participants were identified as potential super-emitters.
Humans ; Male ; Speech/physiology* ; Adult ; Female ; COVID-19/transmission* ; Respiratory Aerosols and Droplets ; Voice ; SARS-CoV-2 ; Time Factors ; Young Adult ; Aerosols/analysis*

The wound mechanism, injury characteristics and treatment principles of anti-armored vehicle ammunition against armored crew in the past 20 years are summarized in this paper. Shock vibration, metal jet, depleted uranium aerosol and post armor breaking effect are the main factors for wounding armored crew. Their prominent characteristics are severe injury, high incidence of bone fracture, high rate of depleted uranium injury, and high incidence of multiple/combined injuries. During the treatment, attention must be paid on that the space of armored vehicle is limited, and the casualties should be moved outside of the cabin for comprehensive treatment. Especially, the management of depleted uranium injury and burn/inhalation injury are more important than other injuries for the armored wounds.
Humans ; Uranium/analysis* ; Respiratory Aerosols and Droplets ; Motor Vehicles ; Burns/therapy* ; Multiple Trauma

Objective: To systematically evaluate the efficacy and safety of rock salt aerosol in the treatment of respiratory tract diseases. Methods: In June 2021, the clinical randomized controlled trial literatures of rock salt aerosol therapy for respiratory tract diseases were searched from CNKI, Wanfang, VIP, Cochrane Library, PubMed database and EMBASE database. Cochrane risk bias evaluation tool was used to evaluate risk bias, Revman 5.4 and Stata16 were used to conduct meta-analysis, TSA 0.9 was used to conduct sequential analysis of trials, and gradepro was used to evaluate evidence quality. Results: A total of 21 literatures were included. According to whether the subjects received rock salt aerosol therapy, they were divided into the experimental group (1125 people) and the control group (973 people) . Compared with the control group, the total clinical effective rate (RR=1.22, 95%CI: 1.15~1.29, P<0.001) , forced expiratory volume in one second (FEV(1)) (WMD=0.20, 95%CI: 0.09~0.31, P<0.001) , percentage of FEV(1) in the predicted value (FEV(1)%) (WMD=5.06, 95%CI: 3.47~6.65, P<0.001) , forced vital capacity (FVC) (WMD=0.22, 95% CI: 0.16~0.27, P<0.001) , maximum expiratory flow (PEF) (WMD=21.312, 95%CI: 9.189~33.435, P=0.004) of experimental group were higher. TSA test shows that the difference conclusions of total effective rate, FEV(1), FEV(1)%, FVC and PEF were reliable, but the conclusion of FEV(1)% needs to be treated with caution; Three literatures reported the adverse reactions in the experimental group; GRADE evidence quality evaluation showed 3 very low-quality evidences and 2 low-quality evidences. Conclusion: Rock salt aerosol therapy combined with conventional therapy has a certain effect on the treatment of respiratory tract diseases, which needs to be further confirmed by high-quality evidence.
Humans ; Respiratory Aerosols and Droplets ; Forced Expiratory Volume ; Vital Capacity ; Respiratory Tract Diseases