Musculoskeletal
Injuries in the Masonry Trade
(Taken
from Construction Safety Magazine, Construction Safety Association
of Ontario, Vol. 10, No. 3, Autumn 1999)
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By Nadine Marks, B.Sc.
(P.T.), Project Coordinator, CSAO
Construction
Safety Association of Ontario
The Ontario Masonry
Contractors Association (OMCA) asked that the Workplace Safety and Insurance
Board (WSIB) partner with the Construction Safety Association of Ontario
(CSAO) to analyze trade activities with a high risk of causing work-related
musculoskeletal disorders (WMSDs). These injuries in the masonry trade
primarily involve the lower back. There are also work-related problems
with shoulder and arm injuries. The WSIB/CSAO study focused on nonresidential
jobsites, both indoor and outdoor. The objective was to recommend controls
to reduce or eliminate risk factors for WMSDs.
Ergonomics is the
study of the body's movements and postures in relation to the performance
of a certain task.
The ergonomic analysis
of work activities among bricklayers and mason tenders focused on working
in awkward postures, lifting, and wrist and arm movements in trowelling.
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Masonry workers
may bend forward more than 1000 times per shift. This involves
lifting not only the block, but also the upper body. In addition,
one-handed lifting puts strain on the upper arm, back, and shoulder.
Most workers
wear gloves when placing block. It is well-documented that wearing
gloves reduces the ability to exert gripping force. As a result,
the forearm/hand muscles must contract harder than bare hands,
contributing to increased fatigue and the risk of incurring a
musculoskeletal injury.
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Working in
constricted spaces imposes awkward postures. Depending on the
task, these postures may be sustained for relatively long periods.
Constricted areas also force workers to twist when bending, lifting,
or placing block. This kind of work carries a very high risk of
back injury.
The risks
of musculoskeletal disorder are similarly high for the shoulder
and upper back when blocks are lifted and lowered over and down
reinforcing rods.
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In the masonry trade,
conditions that carry a high risk of work-related musculoskeletal injuries
were identified through site observations and ergonomic analysis.
- Workers often
perform more than 1000 forward bending tasks per shift and are therefore
at risk of developing low-back disorders.
- Workers who have
to lay brick and block above shoulder height increase their risk of
developing shoulder, arm, and wrist problems.
- Masonry workers
are exposed to environmental factors such as wind and excessive heat
and cold. Walking or working on uneven, muddy, or icy surfaces exposes
bricklayers and mason tenders to the risk of slips, trips, and falls.
- Workers generally
use large trowels (12-inch) that enable them to lay more mortar per
application but also increase the risk of elbow and wrist injuries.
- Many workers wear
gloves when lifting and placing block. Gloves actually reduce
grip strength.
- Mortarboards are
typically positioned at or below knee level. This forces workers to
bend forward repetitively -- a contributing factor to low-back disorders.
- Bricklayers often
work in restricted spaces where their freedom of movement is limited.
As a result they must adopt awkward, twisting movements when lifting
and laying brick and block. This increases the risk of musculoskeletal
injury.
- The stress of
maintaining the expected production rate (about 200 blocks or 600 bricks
per day) can lead to muscle tension and greater likelihood of injury.
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Working
against gravity in this awkward posture creates high musculoskeletal
loads and reduces blood flow to muscle and other tissue. The posture
requires that the muscles of the upper shoulder and back lengthen
while they also contract. At the same time, forearm and hand muscles
must be held in a contracted position to maintain grip on the
block while it is being carefully lowered. All of this muscle
activity in an awkward posture requires high energy expenditure
and causes fatigue. |
This mason
is working on the same wall as his taller partner in the photo
at left. But he employs a better technique, reducing significantly
the musculoskeletal risk factors in laying block.
The mortarboards,
however, could be raised higher. Mortarboards are typically
set at or below knee level, forcing workers to bend forward
in order to load their trowels. Repetitive forward bending is
a contributing factor to musculoskeletal back injuries.
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After conducting
and reviewing this ergonomic study of the masonry trade, representatives
of the OMCA, WSIB, and CSAO agreed that corrective action is not only
possible but necessary.
The first step is
for both management and labor to recognize that risk factors exist. The
next step is to work toward controlling or eliminating those factors.
Correction requires
commitment and continuous improvements at various levels of a company,
with attention not only to specific job tasks but to the structuring and
supervision of work and the development of appropriate policies and procedures.
A systematic approach can help to reduce both injury rates and compensation
costs.
Specific recommendations
of the study include the following:
- Develop information
and training on trade-specific ergonomic practices, including work pacing.
- Identify best
practices to reduce injuries and increase efficiency -- for instance,
mast-climbing work platforms.
- Implement a pre-job
exercise program and improve work/rest cycles to reduce fatigue and
injury.
- Plan and organize
sites to facilitate access, reduce unnecessary materials handling, and
avoid work in constricted spaces that force workers into awkward postures
and twisting movements.
- Use height-adjustable
mortarboards to reduce forward bending. Similarly, keep platforms for
stocking brick and block no lower than knee-height.
- Educate workers
regarding the importance of using a trowel suited to their individual
size and strength.
- Work with manufacturers
to develop more ergonomically favorable bricks and blocks.
These recommendations
are meant to help eliminate or reduce risk factors surrounding work-related
musculoskeletal disorders in the masonry trade.
The recommendations
are only a starting point. Further development and implementation should
involve those directly concerned -- Ontario's bricklayers and mason tenders.
This document appears in the eLCOSH website with the permission of the author
and/or copyright holder and may not be reproduced without their consent.
eLCOSH is an information clearinghouse. eLCOSH and its sponsors are not
responsible for the accuracy of information provided on this web site, nor
for its use or misuse.
This document was published in 1993 as OSHA Fact Sheet No. 93-03. This is
one of a series of fact sheets highlighting U.S. Department of Labor programs.
It is intended as a general description only and does not carry the force
of legal opinion.
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