5.2 PHYSICAL HAZARDS
5.2.1 Heat
5.2.1.1 Hazard Location
The laundry, boiler room, and kitchen are known as hot environments. Other departments of the hospital may also be hot during the summer months, especially in older facilities that have inadequate ventilation and cooling systems.
5.2.1.2 Potential Health Effects
Heat-related health effects include heat stroke, heat exhaustion, heat cramps, fainting, and heat rash (NIOSH 1986b).
5.2.1.2.1 Heat stroke
Heat stroke is the most serious heat-related health effect; it results from a failure of the body’s temperature regulating mechanism. The victim’s condition may be characterized by hot, dry skin, dizziness, headache, thirst, nausea, muscular cramps, mental confusion, delirium, convulsions, or unconsciousness. Body temperature may exceed 105°F (41°C). Unless quick and proper treatment is rendered, death may occur.
Workers with any of these symptoms should be immediately removed to a cool area and attempts should be made to reduce body temperature by soaking the clothing thoroughly with water and fanning vigorously. A physician should be called immediately.
5.2.1.2.2 Heat exhaustion
Heat exhaustion is caused by the loss of large amounts of fluid and sometimes by the excessive loss of salt through sweating. The symptoms of heat exhaustion resemble those of heat stroke, but unlike the latter, the symptoms are milder and victims sweat and have a body temperature that is normal or only slightly elevated.
Victims of heat exhaustion should be removed to a cool place and given large amounts of liquids to drink. In mild cases, recovery is usually spontaneous with this treatment. Severe cases require the attention of a physician and may take several days to resolve.
5.2.1.2.3 Heat cramps
Heat cramps are painful muscle spasms that occur from salt loss through sweating and from the dilution of body fluids through drinking large quantities of liquids. The cramps usually occur in those muscles that are being used for work. Cramps may occur during or after work and may be relieved by drinking salty liquids. Workers on low sodium diets should consult a physician before beginning work in a hot environment.
5.2.1.2.4 Fainting
One mechanism for dissipating body heat is dilatation of blood vessels, which may cause fainting when blood pools in the legs and reduces circulation to the brain. This problem may affect unacclimatized workers who spend much of their time standing with little movement. Recovery may be hastened by placing the victim on his back with the legs elevated. Workers who must stand for long periods can prevent fainting by moving around.
5.2.1.2.5 Heat rash
Heat rash, prickly heat, results when the skin remains wet with sweat for prolonged periods and evaporation is reduced or absent. These conditions cause the sweat glands to become plugged and irritated, leading to development of a rash. Although it is not a health-threatening condition, heat rash may be sufficiently irritating to impair the worker’s performance. Heat rash can be prevented by keeping the skin dry and clean.
5.2.1.3 Standards and Recommendations
NIOSH has recommended an occupational standard for workers exposed to hot environments, Figures 5-1 and 5-2 (NIOSH 1986a). The standard includes recommendations for exposure limits, medical surveillance, posting of recommendations for exposure limits, medical surveillance, posting of hazardous areas, protective clothing and equipment, worker information and training, methods for controlling heat stress, and recordkeeping. The recommendations consider both acclimatized and unacclimatized workers and combined effects of metabolic and environmental heat (NIOSH 1986a). Table 5-3 provides data for estimating metabolic heat.
The values in Table 5-3 can be used to calculate the approximate total metabolic heat (Ht) consumed by a worker performing various tasks.
Figure 5-1. Recommended exposure limits (REL) for unacclimatized workers. Data assume a standard worker having a body weight of 154 lb. (70 kg) and a surface area of 19.4 ft 2 (1.8 m2). Adapted from NIOSH 1986a.
Figure 5-2. Recommended exposure limits (REL) for acclimatized workers. Data assume a standard worker having a body weight of 154 lb. (70 kg) and a surface area of 19.4 ft 2 (1.8 m2). Adapted from NIOSH 1986a.
| Body position and movement: |
|
18
|
26
|
150
|
To 150 add 48 for every meter of rise
| Type of work: |
|
|
24
|
54
|
|
60
|
108
|
|
90
|
150
|
|
210
|
300
|
420
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540
| Basal Metabolism | 60
| *A standard worker is assumed to have a body weight of 154 lb. (70 kg) and | |||||||||||||||||||||
Total metabolic heat is calculated using the following formula:
For example, a worker who is standing and using both arms to perform a task would be producing metabolic heat as follows:
Thus
Ht = 36 kcal/hr + 150 kcal/hr + 60 kcal/hr = 246 kcal/hr
the metabolic heat is used with the wet bulb globe temperature to determine exposure limits for work (Figures 5-1 and 5-2).
5.2.1.4 Environmental Monitoring
the most common and direct way of measuring heat exposure is with wet bulb and globe thermometers and the wet bulb globe temperature (WBGT) index. The WBGT index combines the effects of radiant heat and humidity with the dry bulb temperature. This method is inexpensive and simple (NIOSH 1986a). 5.2.1.5 Exposure Control Methods
A good source of general information on the health effects and control of occupational heat exposures is Criteria for a Recommended Standard: Occupational Exposure to Hot Environments (NIOSH 1986a). Listed below are some specific steps for reducing heat stress in hospital workers exposed to hot work areas (NIOSH 1986a, NIOSH 1986b):
5.2.2 Noise
Noise is any unwanted sound; it is created by sound waves, which are rapid vibrations in the air. Sound has three characteristics: frequency, pitch, amplitude (intensity) and perceived loudness. Frequency is measured in cycles per second, or Hertz (Hz) and sound intensity is measured in decibels (dB). The decibel scale is a logarithmic measure of intensity. When a sound increased by 10 dB, it is 10 times as intense and is perceived as being twice as loud. Loudness, unlike intensity, is a subjective perception of sound and cannot be measured by instrument.
5.2.2.1 Hazard Location
Exposure to high levels of noise in the workplace is one of the most common job hazards, and despite the popular image of hospitals as quiet zones, they can be noisy places. In a 1979 survey of noise levels in 26 hospitals, five work areas were identified as noisy enough to reduce productivity (Seidletz 1981): the food department, laboratory, engineering department, business office or medical records department, and nursing units.
5.2.2.2 Potential Health Effects
The ear changes air pressure waves into nerve impulses that the brain interprets as sound. Hair cells in the inner ear stimulate nerves that carry the message to the brain. Loud noise damages these nerves and decreases hearing acuity. This decrease is called a temporary threshold shift. Such shifts can be reversed if there is enough rest from high noise levels, but exposure to loud noise for many years leads to irreversible hearing loss. Very loud noises of short duration, such as gunfire, can cause a permanent hearing decrement.
Noise may also trigger changes in cardiovascular, endocrine, neurologic, and other physiologic functions, all of which suggest a general stress reaction. These physiologic changes are typically produced by intense sounds of sudden onset, but they can also occur under sustained high-level or even moderately strong noise conditions. Whether repeated noise-induced reactions of this type can ultimately degrade one’s physical and mental health is still uncertain. There are some reports that show that prolonged exposure to high-level noise may lead to physiologic disorders in animals (NIOSH 1972).
In addition to adverse health effects, work in high-noise areas makes it difficult for workers to communicate among themselves, either to relate socially or to warn others of impending danger (e.g. falling equipment or a slippery floor) or to concentrate on critical job functions.
5.2.2.3 Standards and Recommendations
The OSHA occupational exposure limit for noise is 90 dB measured on the A-weighted scale* (90 dBA) as an 8-hr TWA (29 CFR 1910.95). Because the noise exposure limit is time-weighted, the amount of time workers are permitted to spend in a noise exposure area varies according to the noise level, as follows:
5.2.2.4 environmental Monitoring
The OSHA publication Noise Control: A Guide for Workers and Employers (OSHA 1983) is a helpful guide for establishing a noise monitoring and control program. The standard sound level meter is the basic noise-measuring instrument; however, there are noise dosimeters that can measure the integrated (daily) noise exposure. 5.2.2.5 Exposure Control Methods
5.2.2.5.1 Noise abatement programs
A noise survey should be made by trained personnel. If a worker’s noise exposure exceeds the standard, a noise abatement program is required. Such a program should include periodic noise measurement, engineering and administrative controls, hearing protection for use while controls are being implemented, and annual audiometric testing.
5.2.2.5.2 Engineering controls
The goal of the hearing conservation program should be to develop engineering controls to reduce noise exposure. Engineering controls could include enclosure of noisy equipment, acoustical treatment of walls to reduce noise reflection, vibration damping of noisy machines, and replacement of metal-to-metal contact with synthetic material-to-metal contact. Administrative controls can also be used to limit a worker’s exposure time to excessive noise.
5.2.2.5.3 Hearing protection devices
If engineering or administrative controls are not feasible, or if they are in the process of being implemented, hearing protection is required. Many forms of hearing protection are available, including ear muffs and ear plugs. Some are more effective than others depending on the noise level, frequency, and individual fit of the devices. Protection must be effective but reasonably comfortable.
5.2.2.5.4 Methods for reducing noise levels in various departments
5.2.2.5.4.1 Food department The following methods can significantly reduce noise within the food department and still allow sanitary requirements to be met (Seidletz 1981):
5.2.2.5.4.2 Office areas
Noise levels in office areas generally average 68 to 75 dBA. The use of padding under typewriters and sound-absorbing wall hangings reduced noise levels by 13 to 18 dB (Seidletz 1981). 5.2.2.5.4.3 Engineering department
In engineering departments, noise levels range from 78 to 85 dBA, with short bursts as high as 100 dBA. Noise levels around hospital generators may reach 110 dBA. Significant noise reduction can be achieved by isolating the generator area and installing mufflers and using sound-absorbing materials wherever possible (Seidletz 1981).
5.2.2.5.4.4 Nursing units and laboratories
Noise in nursing units and laboratories results from sources such as the ventilation system, intercom system, door closings, telephones, food service carts, radios, televisions, and conversations among staff, patients, and visitors. The results of a hospital noise survey showed that noise levels interfered with speech during the day and with sleep at night (Turner et al. 1975).
Most noise in nursing areas and laboratories can be simply and economically eliminated by the following methods Turner et al 1975:
5.2.2.6 Medical Monitoring
As mentioned earlier, the OSHA noise standard (29 CFR 1910.95) requires audiometric testing, at least once a year, for all workers exposed to noise levels equal to or greater than an 8-hr TWA of 85 dBA.
5.2.3 Ionizing Radiation
5.2.3.1 Types of Ionizing Radiation
Ionizing radiation is part of the natural environment, and since the discovery of X-rays and radioactivity, it has become part of the work environment as well (NIOSH 1977d). Radiation is measured and defined as follows (SI units are given in the definitions):
| Curie | A measure of a substance’s radioactivity. 1 curie (ci) = 3.7 x 1010 disintegrations per second. |
| Absorbed dose | The amount of radiation that the body absorbs. |
| Exposure | The amount of radiation to which the body is exposed. |
| Radioactive half-life | The time required for the radioactivity of an isotope to decrease by 50%. |
| Rem (rem) | Acronym for roentgen equivalent man – the dosage of any ionizing radiation that will cause biological injury to human tissue equal to the injury caused by 1 roentgen of X-ray or gamma-ray dosage. 1 rem = 0.01 sievert (SV). |
| Millirem (mrem) | 10-3 rem. 1 mrem = 0.01 mSV. |
| Rad | Acronym for radiation absorbed dose a unit that measures the absorbed dose of ionizing radiation. 1 Rad = 100 ergs/gm = 0.01 Gray (Gy). |
| Roentgen | Unit of measure for quantity of ionization produced by X-radiation or gamma radiation. 1 Roentgen(R) = 2.58 x 10-4 coulomb/kg. |
The different types of ionizing radiation vary in their penetrative powers as well as in the number of ions they produce while traversing matter.
Ionizing radiation is produced naturally by the decay of radioactive elements or artificially by such devices as X-ray machines. A radioactive element is one that spontaneously changes to a lower-energy state, emitting particles and gamma rays from the nucleus in the process. The particles commonly emitted are alpha or beta particles. X-rays are produced when high-energy electrons strike the nuclei of a suitable target, such as tungsten. When these fast-moving electrons approach the electrical field around the nuclei of the target material, the electrons are deflected from their path and release energy in the form of high-energy electromagnetic radiation (X-rays).
Alpha particles usually have energies of 4 to 8 million electron volts (MeV). They travel a few centimeters in air and up to 60 microns into tissue. The high energy and short path result in a dense track of ionization along the tissues with which the particles interact. Alpha particles will not penetrate the stratum corneum of the skin, and thus they are not an external hazard. However, if alpha-emitting elements are taken into the body by inhalation or ingestion, serious problems such as cancer may develop. Radium implants (radium-226 and radium-222) are examples of alpha particle emitters that may be used in hospitals.
Beta particles interact much less readily with matter than do alpha particles and will travel up to a few centimeters into tissue or many meters through air. Exposure to external sources of beta particles is potentially hazardous, but internal exposure is more hazardous. Examples of beta-particle emitters are the isotopes carbon-14, gold-198, iodine-131, radium-226, cobalt-60, selenium-75, and chromium-51.
Protons with energies of a few MeV are produced by high-energy accelerators and are quite effective in producing tissue ionization. The path length of a proton is somewhat longer than that of an alpha particle or equivalent energy.
X-rays generally have longer wavelengths, lower frequencies, and thus lower energies than gamma rays. The biologic effects of X-rays and gamma rays are better known than those of any of the other ionizing radiation. X-rays may be encountered during the use of electronic tubes and microscopes. Examples of gamma emitters are cobalt-60, cesium-137, iridium-192, and radium-226.
5.2.3.2 Sources of Radiation Exposure
In the United States, natural radiation results in an estimated average dose of about 125 mrem each year (Hamilton and Hardy 1974). In 1973, NIOSH estimated that medical and dental irradiation of patients in diagnostic and therapeutic procedures produced an average dose of 50 to 70 mrem per person per year in addition to natural radiation (NIOSH 1973c).
5.2.3.3 Hazard Location
Radiation exposure usually results from (1) the scatter of X-ray beams caused by deflection or reflection from the main bean, or (2) the emission of gamma rays by patients who are being treated with radionuclides or have therapeutic implants that emit gamma and beta radiation. Ionizing radiation is used in the hospital for (1) diagnostic radiology, including diagnostic X-ray, fluoroscopy and angiography, dental radiography, and computerized axial tomography scanners (CAT scanners), (2) therapeutic radiology, (3) dermatology, (4) nuclear medicine in diagnostic and therapeutic procedures, and (5) radiopharmaceutical laboratories. A radiation hazard may also exist in areas where radioactive materials are stored or discarded. Radiation safety is usually well managed in diagnostic and therapeutic radiology units by the radiation protection officer. Staff in departments where portable X-rays are taken (operating rooms, emergency rooms, and intensive care units, are often inadvertently exposed and inadequately monitored for the effects of radiation exposure.
5.2.3.4 Types and Amounts of Radiation Exposures
The conditions presented by external radiation sources are entirely different from those presented by internal sources. Radiation can be deposited in the body as a result of accidental skin puncture or laceration and subsequent contact with radioactive material. Once inside the body, radionuclides can be absorbed, metabolized, and distributed throughout the tissues and organs. The extent of the effects of radiation on organs and tissues depends on the energy and type of radiation and its residence time in the body, biological half-life, and the radioactive half-life of the radioisotope. But the principal hazard presented by internal radiation sources is the continuous irradiation of cells.
The amount of external radiation received depends on the amount of radiation present, the duration of the exposure, the distance from the source to the worker, and the types of barriers between the source and the worker The effects of radiation from external sources depend on the energy. Unless alpha and beta particles are inhaled or ingested, they are of little concern since they are low energy sources that do not penetrate the outer tissues. Gamma radiation is also rapidly attenuated.
Radiation workers in hospitals receive an annual average dose of radiation that ranges from 260 to 540 mrem. Twelve percent of dental personnel had an average annual exposure of 41 mrem, and 98% had exposures of less than 500 mrem (0.5 rem) (National Research Council 1980). Nuclear medicine technicians who assist in many procedures during a single day may have higher exposures than others who handle radioactive materials. For example, technicians involved in nuclear cardiovascular studies can receive exposures of 2.5 mrem/hr (Syed et al. 1982). Radio-pharmaceuticals have been found contaminating the hands, wrists, lab coats, and urine of technicians and laboratory workers studies (Nishiyama et al. 1980). Angiography is an activity of particular concern. Exposures during these procedures have ranged from 1 to 10 mrems inside the lead apron, and eye exposures have ranged up to 57 mrems inside the lead apron, and eye exposures have ranged up to 57 mrem (Santen et al. 1975; Kan et al. 1976; Rueter 1978). 5.2.3.5 Potential Health Effects
Radiation produces acute effects as well as delayed injuries. The degree of radiation damage depends on which organs and tissues are radiated. In general, the effects of radiation exposure are cumulative.
5.2.3.5.1 Acute effects
Occupational exposure to ionizing radiation is usually localized and can lead to erythema or radiodermatitis. An acute radiation syndrome episode occurs very rarely. such an episode involved whole-body exposure exceeding 100 roentgens during a very short period. Persons with they syndrome usually suffer from nausea, vomiting, diarrhea, weakness, and shock. Following a latent period of 2 to 14 days, symptoms of fever and malaise occur and hemorrhagic lesions of the skin often appear. By the third week, epilation occurs. Internal and external ulceration may appear over the entire body, and bloody diarrhea may occur. Death may result from severe bone marrow depression if the radiation exposure level is high. If the person survives the toxic stage, recovery usually begins by the fifth or sixth week and is essentially complete after a long period (NIOSH 1977d).
A very high dose of radiation can produce symptoms of cerebral edema within minutes and death with 24 hr.
5.2.3.5.2 Chronic effects
Evidence continues to accumulate that low levels of radiation can cause biological damage. Researchers differ over the amount of radiation that is hazardous, but any amount of radiation is assumed to involve some risk. Workers should therefore avoid any radiation exposure. Variables such as age, sex, cigarette smoking, genetic makeup, state of health, diet, and endocrine status may modify the effects of ionizing radiation.
Ionizing radiation can cause gene mutation and chromosomal alteration; it can also delay or impair ell division and interfere with metabolic processes. Cells that normally divide rapidly (e.g. the blood-forming tissues, skin, gonads, and eye lenses) are usually more severely affected than the slower-dividing cells (e.g. the bones, endocrine glands, and nervous system).
Other somatic effects that result from irradiation include several types of cancers (myelogenous leukemia, bone, skin, and thyroid in children) lung and kidney fibrosis, lens opacities, cataracts, aplastic anemia, sterility, radiodermatitis, and shortened life span resulting from accelerated aging.
Prenatal radiation exposure may result in prenatal death from leukemia and morphological abnormalities in the developing nervous system or other organ systems. Sex-ratio changes have been noted. Doses of 10 to 19 rem received by human fetuses have been shown to produce small head size; doses above 150 rem have been associated with mental retardation (Beebe 1981; Meyer and Tonascia 1981).
