(755a) Determination of Particulate Matter in Dental Clinics with and without the Use of Air Purifiers

In light of the SARS-CoV-2 virus pandemic, the Occupational Safety and Health Administration of the US Department of Labor has classified dentistry as one of the very high risk professions for the virus transmission due to the aerosols produced during various dental treatments [1]. Most of the instruments used in standard dental treatments produce aerosols [2, 3]. It has been found that the use of ultrasound equipment in dental treatments can produce aerosols that spread out to distances of up to 2 meters from the patient and that can remain in the air for time periods ranging from 35 minutes to several hours [4]. The production of aerosols and saliva droplets can cause infection via air transmissible microbes. Recent studies have shown that the SARS-CoV-2 virus can be transferred by particulates [5] and a positive correlation has been found between airborne particulates ΡΜ_2.5 and the transmission of other viruses, including the influenza virus [6]. Another study found that SARS-CoV-2 occurs more frequently in airborne particulates with diameters of 0.25-1.00 μm and >2.5 μm [7]. Zhao et al. [8] reported that the use of air purification systems with HEPA and F6 class filters during dental treatments can reduce aerosol concentrations by 54-83%. Another study carried out in a dental clinic found that air purifiers can reduce aerosol concentrations by 80-90% therefore reducing pathogen exposure for both employees and patients [9]. The purpose of this study was to measure the number and concentration of airborne particulates occurring in a dental clinic while performing dental procedures, with and without the simultaneous use of air purifier systems. To the best of our knowledge, no other studies comparing air purification units have been conducted in dental clinics.

Methodology

A Mini Laser Aerosol Spectrometer - IAQ-11R (by GRIMM Aerosol) automatic data recorder was used to determine particulate matter in real time. The Mini Laser captures airborne particulates with diameters of 0.25-32.0 μm and classifies them into 31 size channels. Samples were taken once per minute. The air purification systems applied and compared were the Winix Zero Pro, Aerte, Airocide, Rohnson Pure Air, and VacStation by Eighteeth (Extraoral Dental Vacuum System) systems. Baseline concentrations of airborne particles were initially recorded before air purifier operation. The quantity of airborne particulates was then measured during dental procedures, both with and without the simultaneous operation of the air purifying systems. Statistical analysis of the results was performed using IBM SPSS Statistics Version 25. Results were compared by applying one-way ANOVA analysis of variance and the Tukey test was used to determine statistically significant differences between particulate concentrations (p ≤0.05 was considered statistically significant).

Results

Results showed that the use of air purifiers during dental work can reduce concentrations of particulate matter. Compared to the baseline values, concentrations of particulate matter recorded during dental procedures with operating air purifiers got reduced by 77% for ΡΜ_0.25, 81% for ΡΜ_0.28, 82% for ΡΜ_0.3, and 82% for ΡΜ_0.35. However, under the same conditions but while the treatment area was being aired by open windows alone, particulate concentrations were reduced by 53% for ΡΜ_0.25, 64% for ΡΜ_0.28, 72% for ΡΜ_0.3, and 77% for ΡΜ_0.35. Given that airborne particles with diameters <1 μm are the ones which can enter lung alveoli and potentially harm human respiratory systems [10], use of air purifiers reduces concentrations of particles of this size, thereby improving air quality and reducing potential risk of airborne viral transmission. Continuous operation of air purifiers combined with airing (with open windows) contributes decisively to maintain low particulate levels in and around treatment areas. During dental procedures carried out with the simultaneous operation of air purifying systems, reductions in recorded airborne particulates ranged from 13-69% for ΡΜ₁, 27-67% for ΡΜ_2.5, and 19-23% for ΡΜ₁₀. Experiments conducted with air purifiers that do not possess filters did not show reduced particulate concentrations. The majority of particulate matter captured had diameters of 0.25-0.30 μm, 0.5 μm, and 1.0-4.0 μm, while particles with diameters of 0.65 μm and >5.0 μm were the least commonly observed in all experiments.

Conclusions

The results of this study show a statistically significant difference between the concentrations of particulate matter recorded during dental procedures carried out with and without the simultaneous operation of air purifiers. There is a high risk of SARS-CoV-2 virus contamination in dental clinics due to the aerosols emitted by the use of common dental instruments during standard treatments. Considering the necessity of dental treatments even during the SARS-CoV-2 pandemic, the use of air purifiers is highly recommended as an effective and economic means of reducing virus transmission, especially in small dental clinics / treatment areas.

References

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