Engineering Controls and Technologies to Enhance Safety in the COVID-19 Pandemic Landscape: Lessons for Laboratories and Non-Laboratories

Abstract

Introduction:

The global SARS-CoV-2 pandemic ushered in a new way of life in a short time, with many lasting impacts that have yet to be fully realized. This pandemic threat landscape resulted in massive efforts to increase safety, minimize person-to-person transmission, and rethink how society approaches personal and collective health issues. The buildings and environments in which we live, work, and learn now became environments that pose new risks. As a result, many institutions began asking what improvements could be made to those environments to reduce the spread of infection of SARS-CoV-2 and other infectious diseases.

Methods:

The authors conducted a review of past projects and emerging technologies to evaluate which applications in containment laboratories could represent an example of how engineering controls can improve safety by protecting the workers inside the laboratories as well as the public interfacing the laboratories.

Discussion:

Engineering controls, technology, and safety systems are hallmarks of modern containment laboratories that may provide some context into extrapolating these elements into non-laboratory environments, providing there is coordination with a risk assessment methodology. In this study, the authors explore new technologies proposed for controlling SARS-CoV-2 in heating, ventilation, and air conditioning systems, and potential impacts to the operations and maintenance of those systems.

Introduction

The end of 2019 and the beginning of 2020 saw an unprecedented response to the threat of the SARS-CoV-2 global pandemic. The resulting disruptions to daily life brought forth many changes, including public sector shutdowns, social distancing, indoor mask-wearing, and a host of others. It is likely that many long-term impacts have yet to be felt.

An underlying assumption that prompted the closure of schools, offices, and other places of congregation was an intent to reduce person-to-person transmissibility of the SARS-CoV-2 virus. This virus is a member of the coronavirus genus with a moderate-to-high ability to be transmitted through aerosols and direct contact. ¹ Reducing human interaction and congregation became a primary means to prevent population spread. Inevitably, and with major advancements through the production and distribution of SARS-CoV-2 vaccines, humanity would return to schools and workplaces.

As data emerged that showed SARS-CoV-2 could be transmitted across greater distances (>2 m), attention was given to how society would safely congregate in the future. ² Further evidence that indoor locations create environments propagating the spread of SARS-CoV-2 came from a study of sampling air from a variety of public locales, the majority of which tested positive for the virus. ³ Therefore, a natural line of investigation resulting from the pandemic was what could be done to improve the safety of our homes, schools, offices, hospitals, and other institutions?

Building ventilation systems appear to be a prime target for improvement, given their role in dispersing air throughout an environment. This is not a new concept; rather, it is a hallmark of containment laboratories as described by institutions, including the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC).^4,5 Some estimates suggest that up to 60% of containment laboratory construction cost can be attributed to mechanical air handling systems based on ample evidence that ventilation engineering controls provide secondary worker protection in containment laboratories.

Notably, these engineering controls and technologies are all the result of decades of risk assessments designed at understanding, mitigating, and minimizing the potential for exposure to infectious agents. Therefore, considerations of new technologies and engineering controls resulting from the SARS-CoV-2 pandemic, or other events, are best evaluated in the context of efficacy and risk assessment methodologies working in coordination. In this study, the authors seek to assess emerging technologies in response to the pandemic against efficacy and practicality.

Investigating New Technologies

Emerging threats often create markets for new and improved products. As is usually the case, many are worthy of consideration and provide benefits, whereas other products provide more marketing than efficacy. The ongoing SARS-CoV-2 pandemic is no exception and many entrepreneurs have capitalized on this global threat landscape as an emerging market. CDC remains quick to point out that these new technologies are “emerging” and consumers should do their investigation diligently before pursuing and implementing. ⁶ This includes asking for documented evidence of their claims ensuring that the product provides a level of protection as well as ensuring occupant safety. In this study, we review several examples of emerging products and technologies with the general claim of increasing levels of safety.

Ultraviolet Light in Heating, Ventilation, and Air Conditioning Systems

Ultraviolet (UV) light has been proven to be effective in inactivating many bacteria and viruses, so at first glance this seems like a viable technology. ⁷ UV light has been shown to inactivate SARS-coronaviruses by destroying the outer protein coating. ⁸ Several assumptions make the addition of UV light, or ultraviolet germicidal irradiation (UVGI), a potential attractive safety enhancement. One, the UV light source can be contained in the ductwork so as to not expose any of the UV radiation to occupants in the space.

Two, UV light does not pose any real restriction in ductwork cross-sectional areas, so it has very little impact on overall performance of a heating, ventilation, and air conditioning (HVAC) system. However, the majority of UV light efficacy studies regarding inactivation of virus particles have been conducted in air and surfaces that are at steady state in a controlled environment, not in free-flowing air in a ventilation system. Despite the potential advantages of UV light, little is known regarding the wavelength, duration, and dose required to inactivate SARS-CoV-2 in HVAC systems.

There are disadvantages to UV light as a component of HVAC systems as well. One, UV light must have a direct line of sight to the infectious agents (e.g., virus) it is targeting. Two, the UV light requires some duration to adequately expose the agents. In a typical HVAC system of ductwork, consideration must be given to the placement of the UV source for maximum exposure to the airborne agents and the rate at which airborne agents pass through the field of UV light exposure.

In the case of ventilation systems, flow rates can vary but air typically flows at a rate of several hundred feet per minute to thousands of feet per minute. In a conservative model, let us assume a relatively slow flow rate of 60 feet per minute. If we assume that the velocity of the airborne viral particle is approximate to the flow rate of the air, this means that the airborne viral particles are traveling at a rate of 1 foot per second through the ductwork providing a relatively small window of exposure to the UV light source. This minimal duration is unlikely to provide adequate exposure capable of inactivating the viral particle(s).

To overcome this time duration dilemma, some vendors have suggested using filters to trap viral particles, with the intent of the filters being exposed to the UV light. First, most filters will not trap a virus particle unless it is of high-efficiency particulate air (HEPA)-grade, and secondly, the filter itself represents a potential medium that prevents direct UV light exposure to the viral particles of interest. It is also worth mentioning here the practicality of installing HEPA-grade (or similar) filters in commercial and residential built environments.

The cost of these filters and associated components can add considerable expense, limiting the practicality of this approach. In addition, not all HVAC are designed to have HEPA, or similar, filters added, potentially generating additional expenses. Other proposals suggest continuous lines of UV lights throughout an entire duct network. Although this might give more time exposure to air traveling through ductwork, significant cost is introduced both in installation and ongoing operation of the UV lights. Again, this method appears to be limited in practicality.

In summary, the effectiveness of UV light as a means to inactivate SARS-CoV-2 remains largely unknown because of the lack of data regarding duration of exposure, dose of UV radiation, and wavelength. ⁹ Although UV light may be an acceptable means of viral inactivation of coronaviruses, including SARS-CoV-2, the inclusion of UV light in typical ventilation systems appear to be very limited. Thus, in the case of ventilation systems, it is unlikely that UV light is very effective at inactivating virus particles, and further studies would need to be performed to validate the efficacy of vendor claims to justify the cost of such upgrades.

The authors do note, however, that an earlier position paper published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommend the use of upper-room UVGI, perhaps in combination with in-room fans. ¹⁰ Regardless, the authors feel conclusive evidence remains lacking and additional testing is required to validate this as an effective practical means of HVAC system disinfection.

Intermittent Heating of HVAC Components

Heat has been proven to be effective in inactivating many living things, including bacteria and viruses, and has been considered for a potential mechanism to augment HVAC systems. Several studies have evaluated the efficacy of heat over periods of time as a method of inactivating SARS-CoV-2. ¹¹ Thus, one potential enhancement to HVAC systems to reduce the spread of SARS-CoV-2 may be simply to heat the HVAC components. The concept is simple: a heating coil would be activated within the HVAC system when the built environment is unoccupied (i.e., ventilation system is not running). The heating coil would serve to excessively heat the HVAC components within the air supply system to inactivate viral particles. During the heating cycle, the supply air system is not flowing, so any heat generated remains in the equipment and does not flow into the space that it serves.

Again, the authors have considered the variables (heat and time) necessary for HVAC system heating to be an effective method. In general, temperatures >130°F are recommended for inactivation of SARS-CoV-2. ¹¹ There are many components of traditional and commercial HVAC systems that would be sensitive, if not nonpermissive, of such temperatures. Metal casing will heat up over time but will take several hours to reach a balance above 130°F. Components such as plastic fans, fibrous filters, or insulating materials will not absorb the heat and thus will have very limited temperature rise. Since temperatures ≥130°F are not conducive to times when the building is occupied, this cycle would be performed while air is not moving through the HVAC system. This presents a few complications: one, only the air and/or components present during the heating cycle would be treated. Two, it is unlikely that viral particles are concentrated in one area or component of the HVAC system, causing heating of the entire HVAC system.

Operationally, the energy costs alone with performing an excessive heating cycle every 24 hours will likely be prohibitive. Additional costs would be seen because of thermal stress to the HVAC system components, likely necessitating frequent repairs and replacements. Therefore, the authors conclude that, although excessive heating may be effective for the inactivation of SARS-CoV-2, the practicality of this option remains limited.

Needlepoint Bipolar Ionization

One of the more recent technologies the authors have been asked to review includes needlepoint bipolar ionization. This equipment works in the airstream of a supply system and uses energy to create ions by splitting the water vapor molecules in air into O₂⁻ and H⁺ ions.

In concept, needlepoint bipolar ionization would reduce the viral and bacterial load in a space in two ways. First, the ions would bond with the particulates creating larger particles in which lower efficiency filters found in office or school systems would be more efficient in capturing these particles. Second, the negative ion would remove the hydrogen atom from the pathogen rendering it inactive. ¹²

Recent testing from Illinois Institute of Technology, Portland State University, and Colorado State University demonstrated negligible changes in quantities or loss of particulate matter using bipolar ionization. ¹³ The study also showed that whereas there was a decrease in some hydrocarbons there was also an increase in some oxygenated hydrocarbons, which could result in environmental health considerations.

Organizations such as ASHRAE and the CDC have provided cautionary public statements on the technology indicating the lack of documentation for the efficacy of the technology. Specifically, ASHRAE states:

While variations of these technologies have been around for decades, relative to other air cleaning or disinfection methods, they have a less-documented track record when it comes to cleaning/disinfecting large and fast volumes of moving air within heating, ventilation, and air conditioning (HVAC) systems or even inside individual rooms. This does not necessarily imply the technologies do not work as advertised. However, in the absence of an established body of peer-reviewed evidence showing proven efficacy and safety under as-used conditions, the technologies are still considered by many to be “emerging.” ¹⁴

The authors recommend that evaluation of the technologies discussed in this study, or others, be treated like a risk assessment in a laboratory setting and that performance and efficacy of each type of system are reviewed thoroughly before implementation.

ASHRAE Recommendations

In April of 2020, the “ASHRAE Position Document on Infectious Aerosols” was published to help provide guidance on the use of building HVAC systems to support the reduction of risk of spread of diseases by infectious aerosols. ¹⁰ The recommendations were provided for healthcare and non-healthcare facilities and based on evidence levels “A” (strongly recommended based on good evidence) to “E” (insufficient evidence to provide a recommendation).

From this position document, examples of mitigation measures categorized as strongly recommended include the following:

“Based on risk assessments, buildings and transportation vehicles should consider designs that promote cleaner airflow patterns for providing effective flow paths for airborne particulates to exit spaces to less clean zones and use appropriate air-cleaning systems.

Enhanced filtration (higher minimum efficiency reporting value [MERV] filters over code minimums in occupant-dense and/or higher-risk spaces).

Upper-room UVGI (with possible in-room fans) as a supplement to supply airflow.

Local exhaust ventilation for source control.

Where a significant risk of transmission of aerosols has been identified by infection control risk assessments, design of AIIRs (airborne infectious isolation rooms) should include anterooms.” ¹⁰

From this same report, additional recommendations that scored a “B” (recommended based on fair evidence) include the use of personalized ventilation systems for high-risk tasks, free-standing HEPA filters, and effective temperature and humidity control. ¹⁰

The recommendations and implementation of solutions should be performed as part of a broader risk assessment and with engineering expertise as HVAC systems have highly complex interdependencies that must be considered. For example, increasing the minimum efficiency reporting value rating of filter(s) could impact on the overall pressure drop of an air system, which would reduce the ability to move air through the system and individual spaces. Also, increasing the outdoor air quantity could have detrimental effects on temperature and humidity control if the chiller/refrigeration and boiler systems are not sized to handle the increased load. The increase in outdoor air alone may not have a substantial impact on the control of contaminants without consideration for air change effectiveness, which is largely to do with selection and type of air distribution devices and placement within a space. For a viable solution to be effective, consideration needs to be given for the overall operational impact in risk-based decisions.

Impacts on Operations and Maintenance

Whether a laboratory or non-laboratory setting, the recent pandemic has highlighted unique impacts to ongoing operations and maintenance (O&M) of a facility. Aside from the normal day-to-day activities, the facilities management teams now need to consider how the current and potential future pandemics could impact O&M. Some of the challenges reported to the authors during professional consulting engagements included the following:

Supply chain disruptions have become commonplace during the pandemic, whether in the home or work environment. Facilities that relied on “readily available” or “off-the-shelf” consumables and parts have found them often unavailable. This has forced management teams to look at how they prioritize their critical stock supply, not on just the critical nature of the equipment and system but also on availability of items during a global disruption.

Facility reliance on service providers, equipment vendors, and contract labor has affected O&M tasks. At the onset of the pandemic during the initial “lockdowns” access to many sites and facilities was limited resulting in deferred maintenance. When access was resumed it was in a reduced capacity with restrictions. Requirements for onsite technical expertise from afar were nonexistent in some cases due to travel restrictions. The emotional stress from the pandemic is still being felt with providers questioning whether it is safe to work in laboratory facilities.

In some cases, the science needs and goals were in a position of jeopardy as facility O&M activities were reduced or put on hold.

An emphasis on revisiting disaster recovery plans to include lessons learned from the recent pandemic.

Data collected over multiple years of professional consulting engagements have allowed the authors to apply a general O&M metrics for containment laboratories as a percentage of the total construction cost per year. This metric may increase as O&M priorities are reassessed in the postpandemic landscape.

Existing processes to provide operational assurances under a Continuous Facility Verification will be challenged by the introduction of new technologies for the inactivation of viral agents in HVAC environments. Issues facilities management teams will be forced to reconcile include (1) the additional cost for a desired level of sustained assurance and (2) providing demonstrable evidence to the facility users/staff and service providers that it provides a safer work environment. These concerns apply to both containment and noncontainment facilities.

A decades-long focus on supply chain optimization to minimize costs, reduce inventories, and drive-up asset utilization has removed buffers and flexibility to absorb disruptions. The SARS-CoV-2 pandemic illustrates that many institutions are not fully aware of the vulnerabilities of their supply chain relationships to global shocks. ¹⁵

Other potential supply chain outcomes from the pandemic include the following:

• Enhanced focus on workforce/labor planning

• Understanding and activating alternate sources of supply

• Updating inventory policy and planning parameters

• Preparing for facility closures

• Increasing sensitivity to business continuity over costs

• Supply chain workarounds are now standard.

In summary, institutions must reconcile the potential for escalating O&M costs and requirements because of the pandemic. This is likely to be exacerbated by implementation of new technologies (e.g., UVGI, heated HVAC systems, and others), if chosen, including the additional burden of efficacy against a risk assessment paradigm. Furthermore, institutions must also find innovative means to accept the challenges of a vulnerable supply chain to adequately execute O&M operations.

Summary

The SARS-CoV-2 pandemic has challenged designers, engineers, and biorisk management professionals alike to investigate enhanced methods of protecting workers indoors in disparate settings, including containment laboratories, educational centers, workplaces, and any environment where people congregate. Previous and new technologies, and engineering controls, have surfaced resulting from the pandemic that offered some potential for enhancing safety in commercial, educational, mass transit, and domiciles. The authors have evaluated several technologies for use in building HVAC systems in terms of documented evidence of efficacy, practicality of use and maintenance, and considerations for operational cost.

Many decontamination and disinfection technologies and products are only now being evaluated against rigorous efficacy paradigms, and in some cases have led to lawsuits of false claims. ¹⁶ Issues of fraud continue to be documented by the U.S. Food and Drug Administration (FDA) to help keep the public informed. ¹⁷ Although the desire and need for legitimate effective products is real, many approached these products and technologies with realism and skepticism.

Air handling systems in laboratories and non-laboratories represent an attractive target for the implementation of enhanced safety measures, given the documented aerosol transmissibility of the SARS-CoV-2 virus. ¹ The potential enhancements make use of traditional means of disinfection such as heat, UV light, and ionization, all of which have been documented to be effective at disinfection of a variety of viruses.^7,11 However, the use of these technologies in mechanical air handling systems has not been well documented. Further studies of these applications should occur in practical (e.g., “real world”) settings with rigorous controls to demonstrate efficacy in the reduction of viability of SARS-CoV-2 and other organisms. Facility managers, maintenance personnel, and average consumers should pay close attention to the claims made by vendors of these technologies and rely on credible sources (e.g., ASHRAE, CDC, and FDA) before making investments.

Evaluating the potential enhancement of safety measures by engineering controls and technologies should be conducted against a risk assessment paradigm. It is this risk assessment framework that allowed the concepts of containment laboratories to evolve into what they are today. A similar approach should be taken when considering safety enhancements in non-laboratory environments as well. Perhaps the best lessons that can be derived from containment laboratories to be applied to non-laboratory environments to enhance safety is the risk assessment process.