ASHRAE Journal - October 2021 - 41

COLUMN IEQ APPLICATIONS
related to human health, however,
the individual exposure levels do not
tell the whole story. Occupant health
or disease is infl uenced not only by
exposure to individual constituents,
but also by the interaction of chemicals,
particulate matter, temperature
and water vapor levels. Clearly, this
dramatically increases the number
of variables in an algorithm that connects
indoor exposures to health or
disease. The benefi t to having multiple
inputs in a health impact rating is the fl exibility this
gives to IAQ remediation steps.
Following this logic, adjustments in ventilation and
applications of air cleaning strategies should be guided
by a holistic health impact view of all of the factors that
impact the physiological and immune functioning of
occupants (Figure 1) .
On close inspection of Figure 1 , monitoring individual
Particle Levels
VOCs
Low Humidity
CO2
Ozone
FIGURE 1 Individual indoor exposure metrics vs. occupant health consequences .
AIR QUALITY
Viral Count
MEASUREMENTS
Air Sampling
Particle Counts
Diffusion Monitors,
Photoionization Detectors
Resistance Sensors
Air Monitoring,
NDIR Sensors
Air Monitoring,
Electrochemical Sensors
HEALTH IMPACT
Infections
Penetration Into the Body
Organ Dysfunction
Skin, Mucus Membrane and
Tissue Dehydration
Brain Impairment
Infl ammation of Tissues
MEASUREMENTS
Number of Infected People
Infection and/or Infl ammation
Cognitive Tests, Liver Enzymes
Visual Inspection, Respiratory
Mucus Viscosity, Excess Tearing
of Eyes
Fatigue, Confusion
Pain, Cough, etc.
indoor constituents is more straightforward than quantifying
the health consequences of exposures because an
individual's health is a result of many inputs that can be
diffi cult to identify and quantify. These often elusive variables
include: occupant age, activity levels, liver function
and ability to detoxify chemicals, and other underlying
states of health or disease. Furthermore, as already highlighted,
indoor compounds can interact and become
more impactful than individual chemicals. For example,
when indoor RH is less than 40%, inhaled particles can
gain deeper entry into lungs and cause greater damage
than the same particles in the RH 40% to 60% zone.
What do we need to have a better understanding of the
hidden building conditions associated with acute and
chronic diseases? Do we have to wait for OSHA to discover
a glaring problem after many people have been harmed?
The Economics of Healthy Occupants
COVID-19 has eclipsed debates about the affordability
of building interventions to support human health.
Assessing the economics of building occupancy and
business operations gives us an abundance of reliable
data to quantify the fi nancial rewards of health-oriented
indoor air management.
Creating a real-time and usable database from measurements
of occupant health and productivity would
clarify the impact of the design, operation and exposure
to building materials. Unfortunately, collecting this data
is more complicated than measuring, for example, fuel
consumption and energy effi ciency because metrics
associated with health are more complex. Historically,
health outcomes have been considered outside the
expertise of the construction industry and have
remained largely unmeasured and unregulated, resulting
in an economic stalemate.
Without specifi c health metrics usable in the construction
industry, real estate developers cannot demonstrate
the " value " of design and maintenance choices associated
with improved health and productivity. Meanwhile,
the health costs of occupants in poorly designed buildings
cannot be accurately assessed by investors and
other stakeholders. This obscurity limits incentives to
invest in health-based design as a strategy for competitive
market differentiation.
With accurate and simultaneous tracking of indoor
exposures and concurrent building-related illnesses, we
could implement prevention strategies and regulatory
codes based on knowledge of specifi c health-related and
fi nancial impacts of IAQ.
Now that the potential severity of COVID-19 and the airborne
component of SARS-CoV-2 transmission has been
revealed, the cost-benefi t model for safe IAQ expands
beyond employee productivity and comfort to the very
value of a human life. A return-on-investment model that
includes occupant health needs not only metrics on energy
saved, but also metrics on the short- and long-term costs of
medical care for illnesses associated with poor IAQ.
Health insurance companies calculate the cost avoidance
of common medical expenditures and conclude
that one year of good health is worth $50,000.1 The
Environmental Protection Agency (EPA) takes an
even more holistic approach before mandating a new
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ASHRAE Journal - October 2021

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