The Efficacy of 10 Air Changes Per Hour Ventilation in Controlling Air Contamination in Dentistry

Abstract

Background: Acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) pandemic has heightened the need to protect healthcare workers, including dental. The use of mechanical ventilation, particularly high-efficiency particulate air (HEPA) ventilation, was recommended by UK Health Security Agency with a parameter of 6 air changes per hour (ACH) initially. The recommendation was changed to 10ACH for aerosol-generating procedures (AGPs). There have yet to be any previous studies investigating the effect of these two parameters on air contamination in dental hospitals outside the dirty zone. Therefore, this study aimed to fill this knowledge gap. Methodology: MD8 airscan was used (Sartorius, Epsom, UK) with sterile gelatine filters (80 mm diameter and 3 μm pores; Sartorius) to enable RNA extraction for SARS- CoV-2 Polymerase Chain Reaction (PCR) and with polystyrol culture media plate measuring 116 x 24 mm (BACTair culture media, Sartorius, Germany) for bacterial and fungal colony forming unit (CFU) quantification. Sampling air was performed from outside the dirty zone in open clinical areas with ventilation of 6ACH and 10 ACH when AGPs and non-AGPs were performed in two different dental settings; Barts Health NHS Dental Hospital (RLH) and Sir Ludwig Guttmann (SLG) Dental Centre. Results: The air contamination at 10ACH was significantly lower than 6ACH at baseline (13.83±5.4 vs 68.67±74.73; p=0.019), AGP (177.3±19.04 vs 288.5±108.6; p=0.023), and non-AGPs (114.7±23.69 vs 245.3±37.97; p=0.007) in RLH. In SLG, 10ACH maintained air contamination at 30.33±26.73 and 18.33±11.85 for non-AGP and AGP, respectively, compared to 192±34.64 for non-AGP in 6ACH (p=0.0003). XI Conclusion: This study proves that 10ACH is an efficient intervention to improve the air quality in open bay dental clinics during all types of dental procedures (AGPs and non-AGPs) in different dental settings, large dental hospital and outreach dental clinics, which has close similarity to community dental clinic environment.