Study
Finds Exposure To High Levels Of Noise Increases Blood Pressure
Working in loud places can raise blood pressure levels,
a new study by University of Michigan researchers suggests.
Sally Lusk (http://www-personal.umich.edu/~lusk), professor emerita
of the University of Michigan School of Nursing who has studied
noise's effects on hearing loss for years, said her latest project
gives one more reason for concern.
"The literature suggests bringing down your blood pressure
will help prevent heart disease and stroke," Lusk said, "so
understanding the relationship between noise and blood pressure
is important."
The findings, which are published in the Archives of Environmental
Health, were based on a study in a Midwest auto assembly plant
that connects noise exposure with elevated levels of systolic and
diastolic blood pressure and heart rate.
Because people spend so much of their waking time at work, blood
pressure levels on the job are an important part of health, even
if those levels decline after outside of work, she said.
Lusk and her collaborators studied different types of noise in
the factory setting: continuous "usual" noise (recorded
between 41-103 decibels), elevated continuous noise (found to be
between 46-124 decibels), and spikes in instantaneous loud noises
(113-145 decibels).
While others have looked at blood pressure in factory settings
before, the team took a new approach -- outfitting participants
with mobile monitors to take blood pressure readings and record
noise levels throughout the day. Noise readings were taken every
minute, while heart rate and blood pressure were taken every 10
minutes.
The researchers conclude that blood pressure is more affected
by overall noise exposure while the instantaneous peak noises affect
heart rate. Noise exposure is both acute and chronic, as it seems
to play out physiologically in multiple ways.
An increase in 10 decibels in average noise exposure resulted
in a systolic blood pressure increase of two millimeters of mercury,
the units in which blood pressure is measured. The same effect
came when the difference between maximum and average noise increased
by five decibels.
An increase of 13 decibels in average noise exposure led to a
two millimeter increase in diastolic blood pressure. Lusk noted
that a long-term reduction of 6 millimeters in diastolic blood
pressure has been associated with a 35-percent to 40-percent reduction
in strokes and 20-percent to 25-percent reduction in coronary disease.
Using hearing protection to reduce noise levels entering the eardrum
was significantly associated with keeping systolic blood pressure
lower, and while the effect on diastolic pressure was statistically
significant, the effect was in the same direction, Lusk said.
In hearing protection, previous research demonstrates the importance
of wearing earplugs or earmuffs 100 percent of the time -- even
30 minutes without protection cuts their effectiveness in half,
Lusk said.
Helping workers reduce health problems associated with noise requires
a multifaceted approach, Lusk said. In the best-case scenario,
management would enforce use of hearing protection, appropriate
training would be provided to employees, and reminders like posters
in lunchrooms would explain to employees why hearing protection
matters.
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