Objective/aim To identify small particle concentrations (eight categories: ≤0.1 µm × ≤5.0 µm) induced by aerosol-generating procedures (AGPs; high-speed tooth preparation, ultrasonic scaling; air polishing) under high-flow suction with a 16-mm intraoral cannula with and without an additional mobile extraoral scavenger (EOS) device during student training. Materials and methods Twenty tests were performed (16.94 m2 room without ventilation with constant temperature (26.7 (1.1) °C and humidity (56.53 (4.20)%)). Data were collected 2 min before, 2 min during, and 6 min after AGPs. The EOS device and the air sampler for particle counting were placed 0.35 m from the open mouth of a manikin head. The particle number concentration (PN, counts/m3) was measured to calculate ΔPN (ΔPN = [post-PN] − [pre-PN]). Results Mean ΔPN (SD) ranged between −8.65E+06 (2.86E+07) counts/m3 for 0.15 µm and 6.41E+04 (2.77E+05) counts/m3 for 1.0 µm particles. No significant differences were found among the AGP groups (p > 0.05) or between the AGP and control groups (p > 0.05). With an EOS device, lower ΔPN was detected for smaller particles by high-speed tooth preparation (0.1–0.3 µm; p < 0.001). Discussion A greater reduction in the number of smaller particles generated by the EOS device was found for high-speed tooth preparation. Low ΔPN by all AGPs demonstrated the efficacy of high-flow suction. Conclusions The additional use of an EOS device should be carefully considered when performing treatments, such as high-speed tooth preparation, that generate particularly small particles when more people are present and all other protective options have been exhausted.

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Objectives. The study aimed to analyze different ways to control air quality during/after aerosol-generating procedures (AGPs) in a small skills lab with restricted natural air ventilation in preclinical dental training (worst-case scenario for aerogen infection control). Different phases were investigated (AGP1: intraoral high-volume evacuation (HVE); AGP2: HVE plus an extraoral mobile scavenger (EOS)) and afterward (non-AGP1: air conditioning system (AC), non-AGP2: AC plus opened door). Methods. Continuous data collection was performed for PM1, PM2.5, and PM10 (µg/m3), CO2 concentration (ppm), temperature (K), and humidity (h−1) during two summer days (AGP: n = 30; non-AGP: n = 30). While simulating our teaching routine, no base level for air parameters was defined. Therefore, the change in each parameter (Δ = [post]-[pre] per hour) was calculated. Results. We found significant differences in ΔPM2.5 and ΔPM1 values (median (25/75th percentiles)) comparing AGP2 versus AGP1 (ΔPM2.5: 1.6(0/4.9)/−3.5(−10.0/−1.1), p = 0.003 ; ΔPM1: 1.6(0.6/2.2)/−2.2(−9.3/−0.5), p = 0.001 ). Between both non-AGPs, there were no significant differences in all the parameters that were measured. ΔCO2 increased in all AGP phases (AGP1/AGP2: 979.0(625.7/1126.9)/549.9(4.0/788.8)), while during non-AGP phases, values decreased (non-AGP1/non-AGP2: −447.3(−1122.3/641.2)/−896.6(−1307.3/−510.8)). ∆Temperature findings were similar (AGP1/AGP2: 12.5(7.8/17.0)/9.3(1.8/15.3) versus non-AGP1/non-AGP2: −13.1(−18.7/0)/−14.7(−16.8/−6.8); p ≤ 0.003 )), while for ∆humidity, no significant difference ( p > 0.05 ) was found. Conclusions. Within the limitations of the study, the combination of HVE and EOS was similarly effective in controlling aerosol emissions of particles between one and ten micrometers in skill labs during AGPs versus that during non-AGPs. After AGPs, air exchange with the AC should be complemented by open doors for better air quality if natural ventilation through open windows is restricted.

The pandemic spread of the SARS-CoV2 viruses is leading to the use of new ventilation concepts in Europe. One of these options is the usage of Mobile Air Cleaning Devices. These are used as an alternative to central HVAC-systems (Heating-, Ventilation- and Air Conditioning-systems) and reduce the load of pathogens in the room. However, there are still no consistent methods for evaluating the performances of such devices. Thatswhy the effect on the pathogens, the benefit to the room, and the influence thereof on the room occupants are nearly unknown.This paper presents the measurements and results of different devices in the range of 500 m³/h to 1500 m³/h and beyond. Attention is given to the applied methods to define the different characteristics. Specifically, the parameters of volumetric flow rate, electrical power consumption, sound power, separation efficiency, effect on pathogens, room air flow, draught risk, and effects in the room show the need for development.

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The spread of the SARS Cov2 virus in Europe clearly reveals the need of new ventilation concepts. Schools are considered to be one of the main origins of the spread. Therefore, ways to reduce the possibility of indirect infection in everyday school life are investigated. In this paper, the results of field studies are presented. In the course of these studies, different modes of action (filtration, UV-C, photo-catalysis) and room flow concepts (mixed ventilation, displacement ventilation) were considered. The evaluations of the measurements show how the devices influence the sensations of the students (sound pressure level, draught risk, etc.). Furthermore, it shows how the exhaust air capture works and how the room flow is affected. Therefore, ways to reduce the possibility of indirect infection in everyday school life are sought here.