Theatre Design & Technology - Summer 2022 - 8

Any gathering of scene designers or technical
directors is likely to produce stories,
good and bad, of using dirt on stage.
However, no detailed guidance exists
in our industry for selecting a natural
material to evoke soil on stage. This
is the surprising fact I learned when a
recent production at The Ohio State
University called for 420 square feet of
our stage to be covered in soil. In 2020,
Braden Graves, a student in The Ohio
State University MFA program,
produced
a scene design to accompany a
new script by our cohort of graduate acting
students. Unfortunately, just as the
planning and engineering had begun, the
show was cancelled due to the pandemic.
However, I salvaged the research question
that remained and, with the help
of my colleagues, faculty and staff from
around our campus, and generous folks
in the larger community, was able to address
some of the knowledge gap around
using dirt on stage.
Some Definitions
" Dirt " or " soil " means different things to
different people. For example, a civil engineer
understands dirt as a building material.
By volume, about half of dirt consists
of minerals of various sizes. Sand, silt,
and clay represent the large, medium,
and small sizes, and their relative percentages
define the texture of soil. The
other half of dirt is a fairly even mixture
of air and water, with around 5 percent
left over for organic matter. In agriculture,
soil is defined by the amount and
nature of its organic matter, its potential
to hold water, its resistance to erosion,
and numerous other variables that affect
its fertility. Horticulture represents the
primary consumers of mulch, which is
normally chopped-up bits of various trees
and plants. Silviculture, or tree farming,
is where the materials for mulch often
originate, although some are sourced
from paper mills, land-clearing debris,
and increasingly, from recycled pallet
wood and other construction materials.
When selecting materials to use as
dirt on the stage, we must consider another
diverse group of constituents. For
example, the technical director will likely
work most closely with the material and
will need information on costs, weight,
and moisture content, and may need
to consider acquiring tools most scene
shops rarely use, such as wheelbarrows,
8 | THEATRE DESIGN & TECHNOLOGY | SUMMER 2022
rakes, and shovels. They will also need
information about sourcing landscaping
materials as well as a plan for striking the
material, hopefully to somewhere other
than a dumpster. Costume designers
and technicians will want to know how
the material affects fabric, how badly it
stains, and how often a garment must be
cleaned. Directors and scene designers
may focus on how the material will look
in the space and what ways a performer
is able to interact with it.
For lighting designers, dirt can be
a mixed blessing. As a floor treatment,
dark soil does an excellent job absorbing
light, giving designers greater control and
greatly reducing bounce. If the soil enters
the air, some designers may welcome the
atmospheric effects on lighting beams;
however, few will welcome the dust that
may end up collecting in their instruments.
In fact, this introduces an especially
complicated aspect of using natural
soils on stage: their effect on air quality.
Airborne particulate matter (measured
as PM) can cause a wide variety of health
problems, a fact generally well known in
theatre shops and studios accustomed to
masking and dust collection. However, no
industry standards exist for using dirt in
a performance venue, so additional investigation
is required.
Airborne particulate matter can include
many types of materials, both
organic matter (pollen, mold, bacteria,
dander) and non-organic (dust, ash,
smog, tobacco smoke). Some dangers lie
in the type of material itself. For instance,
crystalline silica, commonly found in
sand, is known to cause silicosis, a
chronic, progressive lung injury, although
generally only after years of prolonged
exposure. Nonetheless, this has led to
a shift toward the use of silica-free sand
on stages. (What is often described as
" silica-free sand " is only free of inhalable
silica dust. All sand contains silica, normally
up to 80 percent but often higher in
natural beach sands. Silica itself is inert
and essentially harmless unless inhaled.)
Particulate matter can also come in
many sizes and, where there is potential
for inhalation exposure, bigger is generally
better. Large, heavy particulates don't
stay in the air as long, and the ones that
do can be captured in the mouth or nasal
cavities if inhaled. Particles that are 10
microns in diameter and smaller (PM10
)
can sneak past those defenses and into
the trachea and bronchial areas. Particles
that are only 2.5 microns in diameter or
smaller (PM2.5
) go even deeper into the
lungs and become respirable. Because
these smaller particles are the most dangerous,
they are commonly the focus of
health studies and regulations.
In the case of particulate matter, existing
exposure regulations fail to adequately
define an acceptable level in theatre
applications. Most regulations focus on
outdoor (ambient) air quality in an effort
to address pollution. In the U.S., these
are set by the Environment Protection
Agency (EPA). Others focus on worker
safety like those set by the Occupational
Safety and Health Administration
(OSHA), while some industry organizations
offer their own recommendations
for particulate levels (e.g., the American
Conference of Governmental Industrial
Hygienists or ACGIH). Even the World
Health Organization (WHO) offers
guidelines.
Looking only at the smaller PM2.5
particles,
as of 2021 the WHO now recommends
a maximum level of 5 µg/m3
for
long-term exposure (averaged over one
year) and a 15 µg/m3
short-term limit (averaged
over 24 hours). The national air
quality standards set by the EPA are less
stringent, with a long-term exposure level
of 12 µg/m3
limit of 35 µg/m3
for health and short-term
(see EPA 2014). Far
more lenient is OSHA with an exposure
limit of 5000 µg/m3
in an 8-hour period,
a figure that controversially has not been
updated since 1971. (This OSHA exposure
limit is for general particulate matter.
Some specific particulate materials
are regulated individually. For instance,
OSHA's short-term limit for inhalable
crystalline silica is 50 µg/m3
.) ACGIH
recommends a threshold limit of 3,000
µg/m3
not to be exceeded at any time
(CDC 2021). To provide some context,
the British Heart Foundation estimates
that smoking a single cigarette in an otherwise
pollution-free day is equivalent
to a short-term PM2.5
(AirQualityNews 2019).
level of 28.8 µg/m3
Assessing Look and Performance
To examine the differences between commonly
available landscaping materials, I
selected a total of 15 types, including all
major varieties of soil, peat, and mulch
available at a leading garden center,
Oakland Nurseries, as well as one type of
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