The proper operation and maintenance of buildings and facilities has become a key factor as countries around the world ease COVID-19 lockdown measures and reactivate economies. As buildings reopen to regular occupancy levels, what steps should businesses, schools, and communities take when looking to keep employees, customers, tenants, and the public safe -- while also protecting the organization?

While building managers, owners and other stakeholders have been focusing on creating socially distant workspaces and installing physical barriers, EHS leaders are advising that maintenance of key systems, including water and ventilation, is critically important to protecting the health of a building’s occupants, especially as they return to buildings that had been left vacant for weeks and months.

Why HVAC maintenance matters

For heating, ventilation, and air conditioning (HVAC) systems, maintenance is critically important for creating healthy environments. This can be complicated by the fact that building populations are low as many employees are continuing to work remotely, leaving companies with vacant spaces. While this may help support socially distanced layouts, it also means that there will be large areas or even entire floors that remain empty.

To address the concern regarding airborne transmission in buildings, various agencies have developed guidance on how to operate ventilation systems while COVID-19 is present. The following list was adapted from a recent white paper titled Ventilation for Industrial Settings during the COVID-19 Pandemic released by the American Conference of Governmental Industrial Hygienists (ACGIH®) Industrial Ventilation Committee in August 2020.

• Increase the outdoor air supply to the maximum allowed by the capabilities of the ventilation system.
• Maintain between 6 and 12 air changes per hour (ACH), which will provide greater than 99% purge in 30−60 minutes.
• Increase the filtration efficiency as high as the filter racks and fan pressure drop will allow (MERV 13 or higher filters).
• Allow the ventilation system to operate continuously if the building is occupied or long enough to allow for several complete air changes following the departure of all building occupants. If the system is shut down or set back overnight, return to full operating conditions prior to occupant return.
• Make sure restroom fans operate continuously and are exhausted directly outdoors with exhausts away from facility ventilation supply intakes. Temporarily disable or discontinue use of hand dryers in restrooms and replace with disposable paper towels.
• General airflow direction should be from cleaner air to less clean air, and processes and workers should be placed on the cleaner side of the airflow pattern within this general airflow pattern to reduce their exposures. Avoid having personal or pedestal fans blow from one person to another.
• Typically, more outdoor air is better. However, high velocity currents passing through open doorways or from a pedestal fan can project viruses hundreds of feet in rapid fashion (although some dilution will also occur). Where inflow occurs at high velocity near workers, attempt to diffuse large air currents by directing or blocking the flow stream to avoid moving the air from person to person. Expanded metal and perforated or unperforated screens are very effective to diffuse large air masses at high velocity.

It is recommended that an industrial hygienist or mechanical engineer conduct a review of a building’s ventilation system prior to making any changes and modifications so that indoor air quality conditions help prevent the spread of the virus.