Noise pollution and the lab environment

Unwanted noise has been a fact of human life for eons. With the advent of the Industrial Revolution and the subsequent development of modern technology, noise-related health issues arose, but it is a problem than has only been sporadically addressed.High workplace-related noise levels are part of the challenge posed by what can only be termed “noise pollution.” Today’s clinical lab is not immune.

Moreover, a number of studies have been undertaken to address noise pollution and how it can alter laboratory findings. From these studies it is clear that chronic exposure to noise results in various levels of hearing loss and, over time, can lead to stress and related ill-health issues that may be reflected in abnormal laboratory test results. This is especially true in the very young, the aged, and the chronically ill.2

To be clear, I am talking about separate two topics related to noise and the clinical laboratory: the effects of excessive noise on human health, which can be reflected in abnormal serology values; and the stressing effect of excessive noise for laboratorians in the workplace.

Impact of noise on general health

Loud noises experienced over an extended period of time can cause hearing loss. Noises over 120 decibels (dB), experienced for even a short period of time, can have an immediate impact, causing permanent hearing damage.3 Because many offending noise sources are very common, they often go unnoticed, blending into the drone of everyday activities.

The most common issue due to noise disturbances is the interruption of sleep both in terms of quality and quantity. Studies have shown that residing near excessive noise sources can increase blood pressure, heart rates/pulses, hypertension, nausea, headaches, mood changes, and anxiousness. Poor cognitive functions, such as speech, reading, attention span, memory, and school performance, have also been seen in children residing in such environments.1, 4-7

Further, hearing loss is the most common occupational disability. It affects approximately 22 million people and costs up to $242 million in healthcare disability compensation annually.8 Even when the National Institute for Occupational Safety and Health (NIOSH) limits are imposed, eight percent of workers could still have some hearing loss.5 The WHO has determined how the following decibel ranges can affect health.9

  • 30–40 dB: Modest effects, mostly sleep disturbances. Most vulnerable are children and the elderly.
  • 40–55 dB: Often see adverse health effects resulting in major life adjustments.
  • >55 dB: Considered a dangerous public health situation with increased and potentially permanent adverse health occurrences.
  • Impact of noise on laboratory findings

    Since the human auditory system is an “open” system even during sleep, it receives a constant bombardment of noises.10 Humans are born with about 16,000 hair cells within the inner ear.3 Noises travel through the auditory system to the brain via the amygdala, which then affects the hypothalamic-pituitary-adrenal (HPA) axis, the regulator that releases stress hormones. Overstimulation results in increased levels of corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and cortisol.11

    Chronic activation of stress hormones can impact bodily functions and cause a number of health issues. Increased cortisol levels have been recorded in individuals living near airports with noise levels of 55-65 dB.11 Increased cortisol levels can have a catabolic effect on protein from muscle, skin, and lymphoid tissues, while inhibiting transport and utilization of glucose.11 Long-term noise exposure has also been associated with issues related to immunosuppression, insulin resistance, diabetes, cardiovascular disease, osteoporosis, and intestinal problems.1,6,11,12

    A study of noise exposure among production line workers over a period of five years showed that glucose and cholesterol levels were lower than a control group.13 Further, CBC results (WBC, RBC, HgB, HCT, MCV, MCH) tended to be higher than the control group. In other studies, noise exposure has been associated with imbalances of other blood components: magnesium, leukocytes (especially eosinophils and basophiles), blood viscosity, platelet count, lymphokines, triglycerides, sex hormones, and retention of sodium in the kidneys. These imbalances further exacerbate wound healing ability, abdominal obesity, pain medication management, stress dysmmenorrhea, hyperadrogenicity in women, and reduced reproductive functions.6,11,14

    Impact of noise in healthcare settings

    Florence Nightingale was quoted as saying, “Unnecessary noise is the cruel abuse of care which can be inflicted on the sick and the well.”14,15 Numerous studies have been done in the hospital setting looking at various noise sources and their impact on patients and staff. Emergency departments, ICUs, operating suites, and NICUs are just a few areas where noise levels can be elevated as part of daily routine activities.14-16

    Noise disturbances that are common in laboratory settings include centrifuges, biosafety/chemical hoods, high-throughput instrumentation, vacuum pumps, and monitors. Other hospital areas are subjected to noise generating ventilators, suction machines, oscilloscopes, paging systems, and fire alarms. In addition, general conversation among staff, patients, and visitors adds to the din, as do TV sets, heavy doors opening and closing, computer printers, HVAC units, and noise associated with the moving of patients and equipment, medication carts, linen carts, and general housekeeping activities.14,17,18

    Anyone who has been a patient in a hospital knows that getting adequate sleep is often difficult. Average noise levels in a hospital may reach 60 dB or greater. Because patients sleep during the day as well as the night, monitoring noise levels throughout a 24-hour period may be required. The Global Health Organization, the WHO, and the Environmental Protection Agency (EPA) all recommend that noise levels within hospital units stay below 45 dB, and preferably no greater than 30 to 35 dB during the day and under 30 dB at night.14,17,18

    Studies have shown that excessive exposure to loud noises during pregnancy may result in high-frequency loss of hearing and potential slow growth development in newborns. It has been suggested that high noise levels can affect cochlear damage of infants in the NICU as well as proper growth development in premature infants. Women with occupational noise exposure of about 80dB were at risk for preterm delivery.1,18,19

    Noise control and prevention

    Most laboratory equipment makers, building engineers, and employers are aware of the need to address occupational noise exposure through implementation of better engineering controls. In hospitals, noise levels can be attenuated to some degree with a careful review of systems and subsequent modification of noise-generating equipment with baffles, mufflers, and the like.20 Hospital personnel should be actively aware of these and other noise sources and attempt to control noise levels by speaking in lowered voices, isolating noise-generating instruments, deactivating unnecessary monitor alarms, avoiding public paging systems, making better equipment selections, and initiating “quiet times.”

    Knowing when one might be exposed to dangerous levels of noise requires testing by a professional and should be considered if the following circumstances occur within one’s workplace:3,21

    • Do co-workers have to speak very loud to be heard?
    • Do you have to turn the car radio volume higher on the way home as opposed to the drive to work?
    • Do you have ringing in your ears after work hours?
      Do you have to ask your family/friends outside of work to repeat what they have just said?
    • Do you have difficulty in hearing higher-pitched sounds, including the phone, doorbell, or alarm clock?

    As individuals, we may have little direct control over most external noise sources. However, taking the time to recognize noise sources within our environment is the first step to reducing noise exposure within the laboratory, the hospital, and home. In some areas, local ordinances may provide oversight of noise control practices and should be explored if necessary. Noise Free America (, a nonprofit organization, focuses specifically on helping to resolve noise pollution issues.

    Professional assistance in measuring noise levels may be sought when necessary. A quick way to determine the presence of chronic noise pollution is to use a sound meter app that is available for most smart phones.22 While the level of accuracy in measuring decibel levels may vary by phone type or the specific app used, it may serve as a basis for further action.

    Be silent about noise no more!

    While a number of regulatory agencies have issued guidelines addressing noise pollution on an industrial or metropolitan scale, it is incumbent upon all of us to recognize and minimize exposure to the various noise sources within our own environment—occupational and otherwise. The fact that studies show that excessive, chronic noise exposure has an effect on various lab analytes, which reflect significant health issues, only underscores the importance of this.

    In 2011, the WHO issued a report20 identifying the number of disability adjusted life-years (DALY, a measurement of the disease burden affecting longevity) lost due to excessive environmental noise in the European Union and the United States. These collective numbers should be a wake-up call to government agencies, employers, employees, and all healthcare workers to raise their level of awareness that noise pollution is a not-so-silent killer:

    • 22,000 years for tinnitus
    • 45,000 years for cognitive impairment in children
    • 61,000 years for ischemic heart disease
    • 654,000 years in general annoyance issues
    • 903,000 years for sleep interferences
    • One million years for traffic-related noise sources.

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