Plants
reduce stress and increase productivity in the workplace
The relationship between a person’s psychological
well-being and the presence of plants has always been
somewhat speculative. Many people instinctively feel
that plants have positive effects but there has been
very little proof – until now. Scientific reports
from researchers at universities in the USA, Netherlands
and the UK shed new light on the effect plants can have
on the stress levels and productivity of office workers.
Virginia Lohr and her colleagues at the Department of
Horticulture and Landscape Architecture, Washington
State University looked at the benefits of adding plants
to a windowless work place – in this instance
a college computer laboratory. Participants’ blood
pressure and emotions were monitored while completing
a simple, timed computer task in the presence or absence
of plants. As Lohr et al state in their study report,
“When plants were added to this interior space,
the participants were more productive (12% quicker reaction
time on the computer task) and less stressed (systolic
blood pressure readings lowered by one to four units).
Immediately after completing the task, participants
in the room with plants present reported feeling more
attentive (an increase of 0.5 on a self-reported scale
from one to five) than people in the room with no plants.”
Click
here to see a copy of Lohr et al’s full report.
Further evidence for productivity improvement with plants
is highlighted in a review of “the effect of healthy
workplaces on the well-being and productivity of office
workers” by John Bergs in the Netherlands. Bergs
cites both Tøve Fjeld and a study carried out
in the Netherlands, at the Winterswijk Tax Office, where
the influence of plants on productivity was closely
monitored (van Dortmont, 2001). The study was carried
out using a control group (without plants) and a test
group (with plants) in comparable areas of the building.
The most significant findings of the study included
improvements in air quality (both measured, and perceived
by the employees) and improvements in productivity.
To cite Bergs’ summary:
- their
productivity improved, especially in terms of efficiency;
- the
strongest link was found with those working at computer
terminals. The most explicit variables are the ratings
assigned for quality of the working environment and
well-being;
- loss
of concentration dropped, i.e. concentration improved
in the test group.
Click
here to see a copy of Berg’s review.
Tøve
Fjeld's study examined the effect of indoor plants on
health and discomfort among office workers. At first
sight this project, conducted by Tøve Fjeld and
others in Norway during 1994 and 1995, seems to be related
to those studies examining sick building syndrome and
the physical effects of plants. However, the conclusions
of this study, conducted in the offices of the Norwegian
State Oil Company (Statoil), suggest that the benefits
observed were more to do with psychological feelings
of well-being rather than any physical effects of the
plants.
The
study was carried out in conjunction with the occupational
health service of Statoil, the largest oil company in
Norway. The 59 Statoil employees in the study each worked
in office cubicles. At the time, there were no plants
in any of the offices. The 59 subjects were split into
two similar groups. During a control period from December
1994 to January 1995 data about 12 different symptoms
were collected. These included fatigue, headache, dry
facial skin and dry skin on the hands, coughing, eye
irritation. For the actual experiment, all offices in
group A (29 persons) were provided with a selection
of common interior plants in February 1995. The same
data were collected every other week during the spring
of 1995 (from week 6 to week 17), both from group A
(whose members had plants in their office) and from
group B (without plants). The plants were moved to group
B in February 1996, with group A serving as the control
(so-called crossover). Once again, the questionnaires
were collected every fortnight. Judged on all symptoms,
a significant improvement can be established when plants
were present in the office. Over the next three months,
considerably fewer health problems were reported. According
to the findings, symptoms decreased by 25%. The key
results were as follows:
- Fatigue and headache fell by 30%
and 20% respectively, when the subjects had plants
in their office;
- hoarseness and a dry throat fell
by around 30% and coughing by around 40%;
- dry facial skin fell by around
25%.
The
author concludes that…
…
the presence of plants can probably result in a positive
change in the psycho-social working environment. The
resultant feeling of well-being also affects how the
individual assesses his/her state of health. Against
the background of the psycho-biological identity and
mankind's positive reaction to nature we can assume
that plants have a particular effect on the sense
of well-being. The individual experience of the subject's
state of health can be at least partly explained by
the following reasoning: an improved sense of well-being
raises the levels of tolerance for irritation. Consequently,
the individual will experience the indoor atmosphere
more favourably if there are plants in the working
environment.
Click
here for a full copy of Fjeld's report.
Additional evidence that plants help to reduce stress
is provided by Helen Russell, in her dissertation “
The effect of interior planting on stress”. Russell’s
study, carried out at Surrey
University, UK as part of her MSc in Environmental
Psychology, attempted to test whether the presence of
plants in a room affected the stress levels of people
undertaking a complex task. Participants were invited
to an office that had no plants, or was heavily planted.
Sensors were attached to the skin of the participants
to record skin conductivity, heart rate and blood pressure.
The participant was allowed to get used to the surroundings
for ten minutes, during which time a base line recording
of their stress level was recorded. After this ten-minute
period, the participant was asked to add up a list of
seventy-eight numbers without the using their fingers
or counting aloud. Distractions such as the sound of
a ringing telephone or traffic noise were played to
them at random intervals. After the test, a further
ten-minute period of rest was allowed.
Of the three types of measurement made, skin conductivity
showed the greatest differences between planted and
unplanted surroundings. In the planted office not only
were stress levels lower, but people recovered from
their stress more quickly than those in the unplanted
office during the ten minute post-test rest period.
The effect of plants on stress may be small and not
apparent in those situations where the task performed
is especially complex. In these situations, a person
will be concentrating so much on the task in hand that
the surroundings may make little impact. However, in
situations where the task being performed is less complex,
or even boring, the soothing effects of the plants may
be more noticeable and have a greater effect on the
people doing the task.
Author:
Mike
Lothian
Additional
material: Kenneth Freeman
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