ASHRAE Journal - November 2022 - 25

COLUMN IEQ APPLICATIONS
example in bacteria is when the cell
membrane detects subtle changes
in temperature, vapor pressure,
oxygen partial pressure, pH or metal
ion concentrations. If these environmental
changes threaten survival of
the bacteria, signals from the membrane
to internal organelles trigger
expression of adaptive traits.
For example, if bacteria encounter
extreme temperatures or dry air,
rates of replication and metabolism
slow, and the cell membrane thickens
while the overall size decreases.
Bacteria can remain dormant in the
air for long periods in this state, but
are highly infectious if inhaled and
rehydrated by a warm and moist
mammalian body.5
Air pollutants, both indoor and
outdoor, disrupt the microbial/
immune system equilibrium. For
example, inhalation of carbon combustion
by-products from traffi c
or other sources reduce protective
microbiota and increase the presence
of potential pathogens in the
upper airways.5 Another example is
that there are proportionally more
pathogenic bacteria in air when levels
of PM2.5 and PM10 are increased,
indicating that pathogenic bacteria
can endure higher concentrations
of air pollutants than commensural
bacteria.6 In short, when air pollutants
are present, more pathogenic
bacteria survive while " good " bacteria
die. These pathogen changes add
to other harmful effects of air pollution
on lungs and cardiovascular
systems.
Factoring the known associations
between the building microbiome,
human microbiome and the environment,
it is possible to develop
machine learning algorithms
that can correlate environmental
FIGURE 4 The road map from IAQ monitoring to quantification of the health
impact. Creating such a benchmark allows HVAC systems to be designed, operated
and maintained to protect occupants from short- and long-term indoor air
exposures.
conditions with health outcomes.
Outcomes based on theoretical
environmental conditions could be
ranked against a template to create a
" Health Score " (Figure 4).
In summary, measurements and
standards exist for IAQ metrics, but
they are largely not based on medical
research. Instead, guidelines are
drawn from observational studies
and expert opinion on the movement
of carbon particles, odors and
thermal comfort. Given that buildings
fi rst and foremost should be
shelters for occupants, this lack of
health visibility on the interplay of
human physiology and IAQ is a missing
piece in our standards. We desperately
need to implement such an
IAQ health standard to control the
impact of individual and combined
indoor pollutants on the human
immune system, infl ammation and
other health pathways. Clearly, professionals
responsible for designing
and operating systems that manage
IAQ systems are in an ideal position
to support occupant health and good
microbes, while diminishing damage
caused by pathogenic ones.
Let's pay attention to the important
lessons from this pandemic, use
the technologies available and not
relive the turmoil of the past several
years.
References
1. Kudo, E., E. Song, L.J. Yockey,
A. Iwasaki. " Low ambient humidity
impairs barrier function and innate
resistance against infl uenza infection. "
PNAS 116(22):10905 - 10910. https://doi.
org/10.1073/pnas.1902840116
2. Kelly, S.J., P. Martinsen, S. Tatkov.
2021. " Rapid changes in mucociliary
transport in the tracheal epithelium caused
by unconditioned room air or nebulized
hypertonic saline and mannitol are not
determined by frequency of beating cilia. "
Intensive Care Medicine Experimental 9:8.
https://doi.org/10.1186/s40635-021-00374-y
3. Mokoena K.K., C.J. Ethan, Y. Yu, A.T.
Quachie. 2020. " Interaction effects of air
pollution and climatic factors on circulatory
and respiratory mortality in Xi'an, China
between 2014 and 2016. " Int J Environ Res
Public Health Dec 3;17(23):9027. https://doi.
org/10.3390/ijerph17239027
4. Croft, D.P., D.S. Burton, D.J. Nagel,
D.J. 2021. " The effect of air pollution on the
transcriptomics of the immune response
to respiratory infection. " Sci Rep 11:19436.
https://doi.org/10.1038/s41598-021-98729-8
5. Taylor, S. 2022. Building 4 Health.
PATENT NO. 11449084.
6. Greeley, D, J. Wagner, J. 2022. Personal
Communication. Global Consulting, Inc.
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https://doi.org/10.1073/pnas.1902840116 https://doi.org/10.1073/pnas.1902840116 https://www.doi.org/10.1186/s40635-021-00374-y https://doi.org/10.3390/ijerph17239027 https://doi.org/10.3390/ijerph17239027 https://www.doi.org/10.1038/s41598-021-98729-8 https://www.ashrae.org/
ASHRAE Journal - November 2022

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