9 Ways to Reduce Contaminants
Facility managers should consider practical steps first
- By Kelly Kleinfelder
- October 01, 2021
To protect students and employees from the SARS CoV-
2 virus that causes COVID-19, air quality should
be a top concern for school and college administrators.
As we have learned more about how COVID-19
spreads, it has become clear that the vast majority of
cases occur through airborne transmission—and improving the ventilation
in campus buildings should be part of a layered approach to
health and safety that includes multiple mitigation strategies.
Ventilation system upgrades can increase the flow of clean air and
reduce the presence of contaminants inside buildings. Here are some
practical steps that facilities managers and other leaders can take
right away to improve campus indoor air quality.
Below are four simple, low-cost strategies for increasing the air
flow in buildings, as well as five additional suggestions for improving
the existing ventilation systems in schools and colleges to prevent the
spread of SARS-CoV-2 and other contaminants. These suggestions
draw on guidance from the American Society of Heating, Refrigeration
and Air-Conditioning Engineers (ASHRAE) and the Centers for
Disease Control and Prevention (CDC).
Introduce more outdoor air into buildings. If you can, open outdoor
air dampers beyond their minimum settings to reduce the
amount of air that is recirculated from HVAC systems. When weather
conditions allow for this, open windows and doors to increase the
flow of air from outside. Even a slightly open window can introduce
beneficial outdoor air.
Increase air flow and circulation. Use portable fans wherever possible
to circulate clean air and direct potentially contaminated air
outside. Avoid placing fans in a way that could cause contaminated
air to flow directly from one person to another. According to the
CDC, one useful strategy is to use a window fan to direct room air
outside. This will help draw outdoor air into the room through other
open windows and doors without generating strong indoor air currents.
Similar results are achieved in larger facilities using gable fans
and roof ventilators, the CDC says.
Make sure ventilation and air filtration systems are working properly.
Check to ensure that all building ventilation systems are operating
correctly and provide acceptable air quality for the occupancy in each
space. Make sure air filters are properly sized. Inspect filter housing
and racks to make sure filters fit correctly and to minimize the
amount of air flowing around, instead of through, the filter. Make
sure restroom exhaust fans are functioning properly and operating at
full capacity when the building is occupied. Inspect and maintain
exhaust ventilation systems in areas such as kitchens, and consider
operating these systems any time the building is occupied.
Adjust HVAC system settings to maximize air flow. Adjust the settings
on HVAC systems to increase total air flow to occupied spaces
wherever possible. Turn off demand-controlled ventilation (DCV)
controls that reduce air supply based on temperature during hours
when a building is occupied.
In buildings where the HVAC fan operation can be controlled by a
thermostat, set the fan to the “on” position instead of “auto,” which
will operate the fan continuously—even when heating or air conditioning
More Complex Solutions
Upgrade HVAC systems to MERV 13 or better. Many schools and
colleges have decades-old HVAC systems that will do little to prevent
the spread of airborne viruses within buildings. An air filtration system’s
ability to remove particulates from the air is rated on a number
system called Minimum Efficiency Reporting Values, or MERVs. This
rating system is helpful in comparing the performance of different
filters; the higher the MERV rating, the better a filter is at trapping
Both ASHRAE and the EPA recommend using the highest-efficiency air filters you can afford to combat the spread of COVID-19 in
buildings, with a minimum efficiency target of MERV 13. According
to the EPA, “Filters with MERV-13 or higher ratings can trap smaller
particles, including viruses.”
The New York City Public School System has spent millions of dollars
to upgrade the HVAC systems within its schools from MERV 8 to
MERV 13 filtration. Upgrading the air filtration within HVAC systems
to a MERV 13 rating or better gives schools and colleges the best
chance at capturing airborne SARS-CoV-2 particles and removing
them from the air inside buildings.
Use HEPA filtration systems to help clean the air.
HEPA stands for “high-efficiency particulate air” filtration, and
these filters are highly effective at pulling impurities from the air and
holding onto them so they can not recirculate. HEPA filters technically
aren’t MERV rated, as the MERV scale stops at 16. However, if
the MERV scale continued beyond 16, HEPA filters would be rated
between MERV 17 and MERV 20. HEPA filters are considered
99.97% effective at filtering particulates as small as 0.3 microns.
HEPA filters can be used inside many HVAC systems, and portable
HEPA filtration systems are also available to clean the air inside individual
classrooms and other indoor spaces.
Consider using UVGI technology to supplement air filtration.
Hospitals and other sterile environments have been using technologies
such as ultraviolet germicidal irradiation (UVGI) for years to
remove harmful contaminants on surfaces and in the air—and this
technique is proving to be effective in mitigating the spread of
COVID-19 as well.
UVGI involves the use of ultraviolet-C (UVC) light rays to kill the
SARS-CoV-2 virus and other contaminants. Direct exposure to UVC
radiation inactivates the virus; however, schools and colleges must use
UVC lamps with caution, as UVC exposure to human skin or eyes can
cause injuries. Using an air purifier or filtration system that contains built-in UVC lamps as well as filters adds another layer of protection,
and this strategy can be more effective than just using a filter alone.
Change air filters regularly. The air filters inside ventilation systems
must be replaced periodically as recommended by the manufacturer.
As the filters become dirty, they also become less effective. Changing
them regularly requires a lot of discipline, not to mention money and
staff time. However, failure to do so could lead to HVAC system inefficiency
and put building occupants at risk from SARS-CoV-2 and
Establish a reliable supply chain for air filters and other supplies.
During a crisis such as the COVID-19 pandemic, supplies such as air
filters and personal protective equipment (PPE) can be hard to come
by. The pandemic has shown that relying on a single supplier can
leave schools and colleges vulnerable when there is a shortage of
materials. Especially when demand is high, it’s best to have access to
a large and diverse pool of suppliers and manufacturers. This strategy
not only helps with ensuring access to supplies; it also helps institutions
procure materials at the lowest possible cost.
In New York City, school custodians are changing the air filters
inside building HVAC systems every three months. With more than
1,700 public schools, this requires several thousands of filters at a
time when supplies are scarce. Working with SDI, the city school
system was able to source replacement filters from multiple suppliers.
The district now keeps a store of filters in a separate warehouse just
for this purpose.
A Multifaceted Approach
The threat from COVID-19 has drawn attention to the need for better
ventilation and air filtration in schools and colleges as part of a multifaceted
approach to health and safety.
By applying these nine strategies, campus facility managers and
other leaders can reduce the likelihood of SARS-CoV-2 transmission
and other airborne illnesses and create a safer environment for students
This article originally appeared in the September / October 2021 issue of Campus Security & Life Safety.