ASHRAE Journal - July 2024 - 44

TECHNICAL FEATURE
The idea of linking our ventilation standards to health
was not acceptable to some members who liked the
19th century paradigm just the way it was and got a set
of strictures added to the Society Bylaws that restricted
ASHRAE's ability to consider contaminant levels. In
response, the Board of Directors created an ad hoc
committee, chaired by future ASHRAE President Lynn
Bellenger, to review how health should be treated in
ASHRAE standards.
The 21st century began with Bellenger's report4
clarifying that health is intrinsic to ASHRAE standards
and ASHRAE's vision should include it. Subsequent
to that, the strictures were removed from the bylaws,
but retained elsewhere; various position documents
have been created relating to health concerns
including on environmental tobacco smoke,5 unvented
combustion,6 mold,7 infectious aerosols8 in addition to
the overarching one on IAQ.1 The last vestige of those
strictures was only removed in January of 2024.
MONETIZING DALYS
C
In the last couple of decades, the research community
has done a lot of work identifying air contaminants
of concern, determining acceptable levels for
those contaminants and developing appropriate
measurement techniques and standards. This
new knowledge has enabled improvements to our
understanding of IAQ and improved standards.
ASHRAE Standard 62.19 has an (optional) Indoor
Air Quality Procedure (Section 6.3) that identifies 15
contaminants and their acceptability level. Meeting
these requirements can allow lower (or require higher)
rates than in the standard's traditional Ventilation Rate
Procedure.
Meeting limit values such as those in the IAQ
omparing the harm from different kinds
of events can be very useful in ordering
priorities, but to determine how one should
allocate resources either privately or in
policy, we need to be able to monetize the
harm. Doing so requires determining the
value of a human life. Recently and with the
encouragement of policy-makers and personalinjury
attorneys, economists have found ways
to do that in what is called a " statistical " human
life. The value varies quite a bit depending on
the socioeconomic status of the region of the
world. Even then there are many statistical and
economic assumptions necessary, and various
methods are used such as from the EPA13 or
HHS.14 For our purposes here, we use a round
number in the reasonable range: $750,000
per DALY for an American. (These costs have
nothing to do with the cost of the related
health care, which is highly dependent on the
specific disease.) Since this value may be much
lower for some populations, there are ethical
considerations to include in making policy, but
they are beyond the scope of this article.
44
ASHRAE JOURNAL ashrae.org J U LY 2024
Procedure can be called a hazard or limit paradigm.
That is, experts and affected parties determine that
there are particular hazards-in this case contaminants
of concern-and set acceptability limits for them. Such
an approach has been used for a long time in a variety
of environments such as the past 50 years by the Clean
Air Act, which led to the U.S. Environmental Protection
Agency's (EPA) National Ambient Air Quality Standard10
for outdoor air. It is also used in occupational settings,
but there it is typically done for short-term (i.e., acute)
exposure. (For the purposes of ASHRAE standards, we
are interested in chronic, as opposed to acute, harm.
That is, we are looking at average exposures rather than
peak ones.)
Toward the end of the 20th century, a different
approach to protecting health was being developed
for all manner of diseases and disabilities: the harm
paradigm. Here the intent was to determine the actual
harm that was being caused, which in our case is from
contaminant exposure in the indoor air. The metric
typically used to quantify harm is the disability adjusted
life year (DALY).11
The advantage to use a DALY approach is that it allows
harm from different sources to be both compared and
combined. It helps prioritize contaminants to allow
one to focus resources. Benjamin Jones12 has previously
described how the harm-based approach may work in
the context of Standard 62.2 using DALYs. DALYs can
even be monetized-which means they can have a dollar
value. (See sidebar " Monetizing DALYs. " )
When looking at large populations, harm is often
called " burden of disease " and assessing that burden
using DALY has been an active area of research. For
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