ASHRAE Journal - September 2019 - 22

TECHNICAL FEATURE

Efforts to Improve ASHRAE and Industry Standards
Helping to update the EPA guidance has reinforced the
authors' opinion that there is an urgent need for a test
method and certification program for portable air cleaners that measures safe removal of gaseous contaminants.
Progress in this area has been slower than the proliferation of consumer products.
AHAM is participating in the arduous process of
international consensus to establish a set of facility
and instrumentation requirements for testing gaseous
contaminant removal by consumer devices. After those
decisions are eventually agreed upon, we might expect
they will begin the even more arduous effort to achieve
international agreement on a test method and rating
system for labels on consumer products. This would be
an important tool to protect the public from ozone and
from potentially unwanted by-products of emerging gas
cleaning technologies.
Devices that claim to remove gaseous contaminants
through electrochemical or photochemical means are
not yet tested nor rated by any independent organization. The EPA guidance clearly states that ozone is a
pollutant to be avoided, and that without independent
testing and certification neither the safety nor the effectiveness of technologies that rely on ozone, plasma,
ionization and photocatalysis (as implemented in air
cleaners in the consumer space) can be easily assessed
at present. The guidance suggests that until testing and
certification is available, the consumer can be aware
that activated carbon filters have been shown to absorb
airborne gaseous contaminants and that chemisorption and contaminant conversion by sorbents such as
potassium permanganate have been widely used for gas
cleaning in the past.
ASHRAE standards could also be improved to assist
homeowners. ASHRAE-funded research confirms that
while MERV ratings are useful for abstract comparison
of products, there is an equally important need to define
the requirements for the frames that holds such filters.
In addition to short run times from oversizing equipment, air bypassing the edges of filters is responsible for
significant shortcomings in particle removal from conditioned spaces. Future ASHRAE standards could contribute to better indoor air quality in homes by limiting
the amount of airflow that can bypass a residential air
filtration assembly (the filter as installed in its holding
frame and surrounding duct).
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Finally, for better health outcomes through air
cleaning we need more filtration operating hours.
For portables, this suggests reduction of current noise
levels. For central systems, the need for more operating
hours means we need to reduce the energy penalty of
continuous fan operation. In the HVAC community, we
know how to do this: supply and return ducts need to
be short, straight, big, airtight and heavily-insulated.
In other words, we need the construction budgets and
architectural designs that allow systems to be designed
and installed the way all HVAC professionals would
choose to do, when indoor air quality excellence is the
consumer's goal.

Summary
Based on the research that supports the 2018 EPA residential air cleaner guidance, there are relatively simple
answers that can help when our friends, relatives or
clients ask for advice about filtration and air cleaning
in their homes. First, let them know that reducing the
concentration of fine particles (PM2.5) has provided the
best-documented health benefits. Next, the best way to
reduce particles is to avoid producing it by not smoking
or vaping indoors, and by exhausting the large amounts
of particles produced by cooking. After those basic steps,
to remove PM2.5 using portable air cleaners, choose
units that have a high CADR rating for smoke. And when
using a central system, choose a filter rated at MERV 13
or higher. Finally, keep in mind that for any filtration
method, longer operating hours provide better particle removal effectiveness, which in turn increases the
potential for health benefits.

Acknowledgments
The authors served as consultants for the 2018 EPA
guidance for air cleaners in the home. We are grateful to
the EPA Indoor Environments Division for the support
needed to generate this article, and also grateful to Jeff
Siegel and Marianne Touchie of the University of Toronto
for the modeling and graphic shown in Figure 4.

References
1. ASHRAE, ed. 2018. Residential Indoor Air Quality Guide: Best
Practices for Acquisition, Design, Construction, Maintenance and Operation.
Atlanta: ASHRAE.
2. EPA. 2018. Guide to Air Cleaners in the Home and Residential Air
Cleaners: A Technical Summary. Washington, D.C.: U.S. Environmental
Protection Agency.

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ASHRAE Journal - September 2019

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