Sally 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 findings 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.
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 ten 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 ten decibels in average noise exposure resulted in a systolic blood pressure increase of two millimetres 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 millimetre increase in diastolic blood pressure. Everyday conversation is about 60 decibels, compared to about 80 decibels for heavy city traffic or running a vacuum cleaner, for comparison, according to the U.S. Occupational Safety & Health Administration.
Lusk noted that a long-term reduction of six millimetres in diastolic blood pressure has been associated with a 35-40 percent reduction in strokes and 20-25 percent reduction in coronary disease.
MEDICA.de; Source: University of Michigan