ASHRAE Journal - November 2021 - 42

TECHNICAL FEATURE
ASHRAE and Ionization
In the Sept. 1966 ASHRAE Journal, a peer-reviewed
article, " Distribution of Ions by Air for Effectual
Control of Electrostatic Charges, " 1 by Duane D.
Pearsall, Member ASHRAE, introduced ionization as a
method to control static potential indoors by creating
an atmosphere essentially saturated with ions of positive
and negative polarity (bipolar). This controlled the
precipitation of infinitely small particles within industrial
cleanrooms, particulate which could, otherwise,
seriously interfere with the cleanliness of both process
and product.
The article noted how important it was to use electric
ionization that incorporated relatively low voltage levels
to create a maximum ionization potential without
the generation of ozone, a known toxic gas.11 Pearsall
concluded his article by stating that at the time there
were no fewer than 300 technical papers relating to
the physiological effects of ionization, that most suggested
some value in the generation or control of
ionization, and that " we have found no information
to suggest that ionization is unhealthy to the human
environment. "
in both polarities.7 When ions are
measured in more polluted environments,
such as inner cities,
naturally occurring ion levels
become depleted and may measure
considerably less.8 Inside buildings
these levels may be diminished even
further as any remaining ions are
depleted during their interaction
with more heavily contaminated
air.8
Various pollutants have the effect
of reducing the amount of naturally
available ionization in ambient air.
The concept of artificially ionizing
the indoor air has been recognized
to replenish the concentration of
ions to a level more consistent with
that of the outdoors, where the air
may be considered cleanest.9
42
Another ASHRAE article " Reduced Outdoor Air
for Auditorium, " appeared in the May 2006 ASHRAE
Journal, authored by Peter F. Johnson, P.E., Member
ASHRAE.12 Johnson discussed a project he designed
using bipolar ionization in combination with ANSI/
ASHRAE Standard 62.1-2004, Ventilation for Acceptable
Indoor Air Quality, using the Indoor Air Quality
Procedure (IAQP), which allowed for combining bipolar
ionization and high-efficiency particulate filters
(MERV 11) to reduce outdoor air ventilation rates. The
project was considered an architectural showcase for
the Brunswick School of Performing Arts Center in
Brunswick, Ohio. With more than a 50% reduction
in outdoor air for ventilation achieved, it was also
awarded a 2006 ASHRAE Technology Award.
The author noted that with bipolar ionization the site
benefited from better indoor air quality along with
a $60,000 savings in initial cost through reductions
in HVAC equipment size. Substantial lifetime energy
savings by reducing the need to heat and cool large
quantities of ventilation air was another contributing
factor that would be an added benefit over the life of
the system.
Ions and Humans
Ions occur naturally and in abundance
in the air around us.7 While
a variety of physiological or health
effects in relation to exposure to air
ions have been reported through
the years, more recent research has
posed doubt to these claims. The
Journal of Negative Results in Biomedicine
published a study10 in which the
authors stated that from a mechanistic
or physical perspective there
is no basis to suspect that electric
charges on clusters of air molecules
(ions) would have beneficial or deleterious
effects on respiratory or
biological function.
Their conclusion upon review of
80 years' worth of scientific literature,
all of which had asserted the
impact of human exposure to air
ASHRAE JOURNAL ashrae.o rg N O V E M B E R 2021
FIGURE 3 The author's (David Schurk's) handheld
ion counter. Peak positive ion concentration
28,140 ions/cc. Reading taken at 12,240 ft
(3731 m) elevation on mountaintop in Colorado.
The ion counter has selectable maximum ranges
of both 2 million and 200 million ions/cc.
ions and their effect on respiratory
and other biological effects, was as
follows: " Despite numerous experimental
and analytical differences
across studies, the literature does
not clearly support a beneficial role
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ASHRAE Journal - November 2021

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