EI has been closely monitoring the ongoing COVID-19 pandemic and documenting its progress and impact in a series of blogs beginning late January. Early in this series we addressed the importance of updating corporate business contingency plans to include key strategies which address the impact of COVID-19 on employees/business operations. EI’s third blog addressed proper personal protective equipment to minimize exposure to the pathogen, including a comparison of the effectiveness of N95 respirators versus surgical masks. 

Given the rapid spread of COVID-19 within the Wuhan Province in China and subsequently throughout the world, the reason for implementation of social distancing to minimize COVID-19 transmission is obvious. Airborne viral contamination originating from an infected individual drops off dramatically as the distance between individuals increase.  This is due to increased dilution ventilation, limitations of aerosol dispersion and aerosol settling rates (with the “aerosol” being moisture droplets originating from infected individuals). Social distancing, or more accurately described as physical distancing, presents numerous challenges in most of our traditional work environments including commercial and industrial facilities. 

As employers continue to implement best business and hygiene practices to address the rapid spread of COVID-19, we should remember the adage, “the solution to pollution is dilution.”  Dilution is one of the solutions when implemented with physical distancing and proper infection control to minimize the potential for exposure to bioaerosols and other airborne contaminants. Over the past 30 years, commercial buildings have been constructed to be highly energy efficient, which continues to present challenges for dilution ventilation and acceptable indoor air quality (IAQ).  HVAC systems within these highly efficient buildings typically recirculate 80-90% of the indoor air to reduce energy costs associated with heating and cooling outdoor air.  Airborne contaminants in the indoor environment, such as volatile organic compounds (VOCs) and particulates from indoor finishes and furnishings, gradually rise as indoor air is recirculated.  Indoor carbon dioxide (CO2) levels have been used as an indicator of dilution ventilation and acceptable indoor air quality. Building occupants inhale oxygen and exhale CO2, resulting in an increase of indoor CO2 levels. Higher CO2 levels generally correspond with poorer indoor air quality.

The ANSI/ASHRAE Standard 62.1-2019: Ventilation for Acceptable Indoor Air Quality specifies the minimum ventilation rates and other measures intended to provide IAQ that is acceptable to human occupants and that minimize the potential for adverse health effects.  ASHRAE and the EPA generally recommend that indoor CO2 levels not exceed a differential of 700 parts per million (ppm) above outdoor CO2 levels.  If the indoor levels of CO2 exceed this differential with outdoor air, the standard recommends dilution of building air with ambient air from the outside, requiring appropriate adjustment in the building HVAC system.  ASHRAE has provided additional resources specific for COVID-19 concerns using the same guiding principles for building air quality.

OSHA has also recently released “Guidance on Preparing Workplaces for COVID-19” (included here). This document specifies tried and true principles using the Hierarchy of Controls. Traditionally, the hierarchy of controls has been used as a framework to determine how to implement feasible and effective control solutions. Although many of the options in the control strategy are not available for the challenges presented by COVID-19, we still have the options for engineering controls, administrative controls, and PPE.   HVAC engineering control options specified in the OSHA Guidance document include the installation of high-efficiency air filters, increasing ventilation rates, and other ventilation modifications. We have explored many of the control options in previous blogs, except engineering controls.  These generally include exhausting internal air, coupled with dilution ventilation to minimize the potential for exposure to airborne hazards. Adjusting commercial HVAC systems to transfer more outdoor air to building interiors, rather than recirculating interior air to save energy costs, results in additional dilution ventilation and improved indoor air quality (IAQ). 

Comprehensive Indoor Air Quality Solutions
EI has been providing comprehensive indoor air quality monitoring services for over 30 years.  Our scientists have advised the CDC, the US EPA, NIOSH as well as other Federal Government agencies and have conducted thousands of building IAQ investigations. If you would like us to assess your building’s IAQ and make recommendations to improve IAQ, EI is prepared to provide recommendations on administrative and engineering controls, as well as advise on the development of business contingency measures and proper PPE use in the face of COVID-19. 

If you have any questions regarding workplace ventilation and indoor quality or other COVID-19 pandemic concerns, please contact Greg Lathan, President of EI, at (919) 459-5223 or [email protected] or Phil Fincher, CIH, CSP, Vice President of Health and Safety, at (540) 797-1034 or [email protected].