Selecting an Air Purifying System

Background

Indoor air quality has become an important aspect for dentists because of the COVID-19 pandemic. To be able to provide care for patients and protect both the patients and staff, dentists must ensure that their practice facilities meet the guidelines set by organizations such as the Centers for Disease Control and Prevention (CDC), the American Dental Association (ADA), and the Occupational Safety and Health Administration (OSHA) regarding reducing the risk of transmission of aerosolized biologicals to patients and staff. The air exchange data dentists need to know, the choices of air-quality systems available, and the factors that must be considered when investing in any air quality management system were outlined.

Air Exchange

The air exchange rate is the amount of times the air in an enclosed space can be processed through a system. Dental procedures create aerosol droplets that can stay in the air and travel considerable distances, so the avoidance of contamination of both air and surfaces requires a high number of air exchanges per hour. Because disease transmission can also occur after the infected person has left the office, a further increase in air exchanges is needed. Increasing airflow also decreases patient turnover time and creates a positive public perception.

In general, a heating, ventilation, and air conditioning (HVAC) system provides about 8 air exchanges per hour in a 1000−cubic foot room. This yields a patient turnover time of 35 minutes. Use of a portable high-efficiency particulate air (HEPA) filtration system at 99.9% efficiency adds 10 air exchanges per hour, reducing patient turnover time to 18 minutes (Table 1 ).

Table 1.

Air Changes Per Hour (ACH) and Time Required for Airborne-Contaminant Removal By Efficiency

ACH	Time (min) required for removal 99% efficiency	Time (min) required for removal 99.9% efficiency
2	138	207
4	69	104
6	46	69
8	35	52
10	28	41
12	23	35
15	18	28
20	14	21
50	6	8

(Source: Data from the Centers for Disease Control and Prevention. Courtesy of Menzzano L: Everything you need to know about indoor air quality in a dental setting. Dent Econ 110:41-42, 2020.)

Air Quality Systems

The CDC recommends the use of a portable HEPA filter while the patient is having an aerosol-generating procedure and immediately after this procedure in dental settings. Portable air purifiers are the most common and efficient solution to increase air exchanges for dental settings, but multiple options are available that remove odors and volatile organic compounds (VOCs). The leading system groups are ionizers, ozone generators, carbon filters, and earth mineral technology.

Ionizers

Ionizers release electrically charged ions that attract particles. The ions then attach to the particles, which causes them to create clumps that settle out of the air.

Ozone Generators

Oxone generators create a chemical reaction with gaseous pollutants rather than particles. The recommended use for these generators is in unoccupied spaces, with use in occupied spaces specifically omitted.

Carbon Filters

Carbon effectively removes odors and VOCs. When chemical additives are coupled with carbon, its efficiency is increased, but the additives are released in filtered air.

Earth Mineral Technology

Three earth minerals are used to capture and neutralize odors and VOCs. No by-products are released into the environment during this process.

HVAC, Source Capture, and Whole Room System Comparisons

HVAC systems are often used to handle entire office systems. Air is forced through a one-point system, then sucked out through various returns. These systems can, however, increase the risk for distributing aerosolized biologicals or contaminants throughout the office.

A source capture system is useful when the risk of a specific exposure or transmission is higher. This could be when the patient’s mouth is open for several hours. The source capture system is positioned above the source to capture the aerosolized products and reduce transmission risk.

Whole room systems can provide protection for an entire room and exchange air continuously. Any contamination would be handled by filtering all the air in the room.

Dentists can find any of these systems to be useful. When choosing a system, the dentist should consider what best fits the needs of the dental office.

Investment Considerations

Dental professionals need to choose air quality solutions that reassure patients and staff about the safety and comfort of the dental office. Ensuring good indoor air quality will help to make patients and staff more confident about returning to the dental office during the current COVID-19 pandemic. Any selection should be considered a long-term investment for the practice.

Considerations when investing in an air purifying system include maintenance requirements for the components of the system, such as filters. The durability of the machine and any warranty that is offered should also be considered. With an increase in the ventilation in each operatory, the dentist is also decreasing patient turnover time, which yields a profitable return on the investment long term.

Staff can be reassured by an air purifying system that not only eliminates pathogens, but also allergens, VOCs, and odors. Good air quality will increase performance and decrease absenteeism in the workplace, which is also a positive component that should be considered.

Clinical Significance.

To reopen a dental facility that has been closed during the pandemic requires that the dentist meet the guidelines for indoor air quality. Investing in an efficient and well-made air purifying system will pay the dentist back in benefits over the long haul. A system that addresses not just pathogens but also allergens and odors will enhance the environment for both patients and staff, so it would be a wise choice for most practitioners.