Ventilation Assessment by Carbon Dioxide Levels in Dental Treatment Rooms

Abstract

It is important for dental care professionals to reliably assess carbon dioxide (CO2) levels and ventilation rates in their offices in the era of frequent infectious disease pandemics. This study was to evaluate CO2 levels in dental operatories and determine the accuracy of using CO2 levels to assess ventilation rate in dental clinics. Mechanical ventilation rate in air change per hour (ACHVENT) was measured with an air velocity sensor and airflow balancing hood. CO2 levels were measured in these rooms to analyze factors that contributed to CO2 accumulation. Ventilation rates were estimated using natural steady-state CO2 levels during dental treatments and experimental CO2 concentration decays by dry ice or mixing baking soda and vinegar. We compared the differences and assessed the correlations between ACHVENT and ventilation rates estimated by the steady-state CO2 model with low (0.3 L/min, ACHSS30) or high (0.46 L/min, ACHSS46) CO2 generation rates, by CO2 decay constants using dry ice (ACHDI) or baking soda (ACHBV), and by time needed to remove 63% of excess CO2 generated by dry ice (ACHDI63%) or baking soda (ACHBV63%). We found that ACHVENT varied from 3.9 to 35.0 in dental operatories. CO2 accumulation occurred in rooms with low ventilation (ACHVENT ≤6) and overcrowding but not in those with higher ventilation. ACHSS30 and ACHSS46 correlated well with ACHVENT ( r = 0.83, P = 0.003), but ACHSS30 was more accurate for rooms with low ACHVENT. Ventilation rates could be reliably estimated using CO2 released from dry ice or baking soda. ACHVENT was highly correlated with ACHDI ( r = 0.99), ACHBV ( r = 0.98), ACHDI63% ( r = 0.98), and ACHBV63% ( r = 0.98). There were no statistically significant differences between ACHVENT and ACHDI63% or ACHBV63%. We conclude that ventilation rates could be conveniently and accurately assessed by observing the changes in CO2 levels after a simple mixing of household baking soda and vinegar in dental settings.

Dentist Related Factors Associated with Implementation of COVID-19 Protective Measures: A National Survey

“…The potential acquisition and transmission of the SARS-CoV-2 virus in the dental setting [7,27,28], particularly during aerosol generating dental procedures [6,[28][29][30][31], elicits questions about adherence to recommended protective measures. Due to the potential risk of transmitting the SARS-CoV-2 virus in the dental setting, we analyzed dentists' adherence to protective measures, dentist related factors associated with the implementation of protective measures and their link with presumed positivity rate of dentists as well as their perceived risk of infection transmission.…”

Application of recommended preventive measures against COVID-19 could help mitigate the risk of SARS-CoV-2 infection during dental practice: Results from a follow-up survey of French dentists

“…However, during non-aerosol generating procedures, such as clinical interviewing or examination, the patient can talk, cough, scream or cry, all of which can also cause saliva projections and produce contaminated aerosols [ 24 ]. Wearing specific PPE (in particular FFP2, FFP3 or (K)N95 masks) should be warranted, including during non-aerosol generating procedures, with an emphasis on ventilation that can be indirectly monitored through the usage of CO2 readers [ 25 ].…”

Analysis of Impact of Natural Ventilation Strategies in Ventilation Rates and Indoor Environmental Acoustics Using Sensor Measurement Data in Educational Buildings

“…The aim of this method is to determine the ACH . In fact, the decay method consists of increasing the CO 2 concentration by using a CO 2 generation source (e.g., dry ice) [ 50 ] in the classroom until a homogeneous and well-mixed mixture is reached [ 16 , 51 , 52 ]. Subsequently (without source and unoccupied) the rate of decrease of the CO 2 concentration under the different configurations is determined.…”