Introduction
Former U.S. Surgeon General William H. Stewart said in 1978, “Calling noise a nuisance is like calling smog an inconve- nience. Noise must be considered a haz- ard to the health of people everywhere.”
A number of studies have shown that high noise levels can contribute to sig- nificant cardiovascular effects and even exposure to moderately high noise levels during a single eight-hour period can a statistical rise in blood pressure of five to ten points and an increase in stress[1-4); Vasoconstriction or narrowing of the arteries, and increased incidence of coronary artery disease. In addition, chronic exposure to noise may cause noise-induced hearing loss.
The degree of annoyance from noise produced by multiple sources is not fully understood but has been identified as a problem in environments operating equipment with varied noise levels and frequencies. There is evidence that com- bined sources of noise pollution lead to an increased level of stress and aggrava- tion which can have a negative impact on efficiency, health and quality of work.
Noise levels are typically expressed in decibels (dBA), which is a logarithmic ratio of the observed level compared to a standard. Table 1 includes the decibel level of a few common activities to pro- vide the reader with an understanding of the intensity of typical noise levels.
In the workplace, noise pollution is generally considered to be an issue once the noise level is greater than 55 dBA. Approximately 35 to 40% of workers in office settings find noise levels from 55 to 60 dB (A) to be irritating. To provide a healthy, safe and stress free environ- ment, the laboratory manager should ensure that the noise level should be kept at a suitably low level. While the overall noise level in a laboratory comes from a variety of sources, an important approach for minimizing laboratory noise is the selection of instrumentation and ancil- lary equipment which are designed to minimize the noise generated and meet regulatory guidelines. Two instruments operating at 52 dB produces a noise level of 58 dB; adding a third instrument operating at 58 dB yields a noise level of 62.5 dB.