Air Quality in a Dental Skills Lab during the SARS-CoV-2 Pandemic: Results of an Experimental Study

Christian Graetz; Naomi Sayk; Paulina Düffert; Ralf Heidenreich; Christof E Dörfer; Miriam Cyris

doi:10.1155/2022/9973623

Air Quality in a Dental Skills Lab during the SARS-CoV-2 Pandemic: Results of an Experimental Study

Int J Dent. 2022 Jun 24:2022:9973623. doi: 10.1155/2022/9973623. eCollection 2022.

Authors

Christian Graetz¹, Naomi Sayk¹, Paulina Düffert¹, Ralf Heidenreich², Christof E Dörfer¹, Miriam Cyris¹

Affiliations

¹ Clinic for Conservative Dentistry and Periodontology, University Hospital Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, Haus B, Kiel 24105, Germany.
² Institute of Air Handling and Refrigeration, Bertolt-Brecht-Allee 20, Dresden 01309, Germany.

Abstract

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.