Physiological Health Concerns

Composting workers are subject to the hazards generally associated with performing physical labor near large equipment in an outdoor environment including noise, physiological stress, extreme heat and cold and fatigue.

Noise

Heavy equipment and processes of composting can be noisy, to the point of being potentially damaging. As most loud noise does not produce pain, hearing damage typically happens so gradually that there is no warning or indication that injury is taking place. The OSHA standard on noise (does not apply to agriculture) endeavors to reduce exposure to levels below damaging levels. The level of noise considered acceptable is an 8-hour time-weighted average of 90 dBA (dBA is decibels, a measure of noise intensity, weighted on the “A” scale, which gives more weight to exposure to higher-pitched noises). For levels of noise higher than 90 dBA, the time of exposure allowed for an employee decreases. At noise levels of 115 dBA, the amount of exposure allowed per day drops to 15 minutes.

If noise exposures equal or exceed an 8-hour timeweighted-average of 85 dBA, the employer must institute a hearing conservation program, which requires monitoring of noise levels. Equipment used at composting sites for wood chipping, shredding, grinding, turning piles, or other tasks has been reported as exceeding 90 dBA; with shredders as high as 98 dBA. Thus the compost site’s equipment should be evaluated to determine the exposure of the employees, along with the length of time the equipment is typically used.

A hearing conservation program requires audiometric testing of employees’ hearing to establish a baseline level for each employee and note trends that indicate hearing damage. The program should also reduce exposure using administrative or engineering controls or, if not feasible, personal protective equipment. For some equipment, an enclosed cab may serve as an engineering control that sufficiently reduces the noise exposure for the operator. When acquiring equipment, noise hoods and mufflers should be specified and then these should be properly maintained. For people running chippers and grinders, personal protective equipment such as ear plugs or ear muffs are needed. If staffing levels permit, it may be possible to reduce exposure by an administrative control – such as rotating workers among a variety of tasks so that the actual duration of exposure per day does not exceed the OSHA standard.

Physiological Demands: overexertion, sprains, or strains (ergonomics)

The daily tasks involved in operating a composting facility can be physically demanding. Frequently, the work requires heavy lifting and prolonged postures (such as operating heavy equipment). These stressors can be compounded by exposure to heat or cold and the ultraviolet light from the sun.

Ergonomics refers to the interaction of humans with their working and living environments. Ergonomic injuries such as overexertion and fatigue can occur when operating heavy equipment with repetitive use of machine controls and prolonged sitting. These tasks could involve acute and/or repetitive injury to muscles and joints. Musculoskeletal injury can be triggered by direct trauma (e.g. falls, impact and bruising) or a single over-exertion (e.g. pulling a muscle while lifting). Repetitive strain can result from static or dynamic work including prolonged sitting, holding the muscles in a tense, fixed position for extended periods, such as carrying something over a long distance; holding tools continuously, bending the wrists to hold or repeatedly move a tool or prolonged exposure to vibrations. Typical symptoms of repetitive strain include soreness, pain, discomfort, redness and swelling, limited range of motion, stiffness in joints, weakness and clumsiness, numbing, tingling sensations (“pins and needles”), popping and cracking noises in the joints, and “burning” sensations. The symptoms occur more readily as people age. Repetitive trauma does not allow for complete repair of the tissue during rest. In the worst stage, pain persists even at rest, and sleep is often disturbed. Severe pain, limited mobility or muscle weakness may make it impossible to perform most tasks.

Preventing ergonomic injuries involves evaluating the job for risk factors and obtaining symptom reports and observations from workers. Often the best ideas and solutions come from the people doing the work, especially if they know the risk factors. Job analysis tools and checklists are available on OSHA’s website (http://www.osha.gov). Table 10.3 list some general risk factors that reflect the body’s limitations, along with several suggested solutions. It is important to report injuries at their earliest stages so that the risk factors of the job or task can be evaluated and modified or eliminated.

Heat Stress

Heat stress occurs when the body is subjected to temperatures that cause the core temperature to stay above 100.4ºF (38ºC), over the course of the workday. Sweating and the surrounding ambient air simply cannot cool the body sufficiently. Wearing protective clothing or a respirator can add to the risk. Workers may notice symptoms of irritability, low morale, increased numbers of errors or increased frequency of unsafe behavior. Usually, adaptation to heat exposure takes about 5–7 days; so abrupt changes in the weather can produce more discomfort than a gradual change in air temperature, which gives the body time to adjust its temperature and pulse rate. People with chronic illnesses of the heart, lung, kidney, or liver tend to have lower heat tolerance and may be at greater risk. In this situation, seek the advice of a physician.

Prolonged heat stress can lead to related disorders such as fainting, prickly heat rash, heat exhaustion and heat stroke. Heat exhaustion and heat stoke are especially serious and require immediate attention. Heat Exhaustion should be suspected if a worker appears disoriented or confused or experiences inexplicable irritability, malaise, dizziness, lightheadedness, headaches, upset stomach, vomiting, decreased or dark-colored urine, fainting or passing out; pale, clammy skin. If any of these symptoms appear, the worker should be moved to a cool location with rapidly circulating air for rest. Loosen and remove any heavy clothing. Have the person drink cool water (about a cup every 15 minutes) unless he/ she is sick to the stomach. Cool the person’s body by fanning and spraying with a cool mist of water or applying a wet cloth to the person’s skin. Keep the person under observation. Call for emergency help if the person does not feel better within a few minutes. If sweating stops and skin becomes hot and dry, the person may be experiencing heat stroke and immediate emergency care with hospitalization is essential.

Hygiene practices can relieve some of the heat stress or assist in acclimation to abrupt changes in the weather. Such practices include:

Fluid replacement -- Drink small quantities frequently (5–7 ounces every 15–20 minutes). Do not depend upon thirst as a warning. Salt intake in a normal diet is usually sufficient to meet salt demands. However, if workers are not acclimated to hot weather, consider beverages containing about 0.1% salt. Workers on salt-restricted diet should never use salt tablets without consulting a physician.
Training and self-determination -- By providing accurate verbal and written instructions and training on heat stress, workers can limit heat stress and recognize symptoms in themselves and others. Managers and workers themselves can adapt to hot days by leveling out the work effort over the allocated time, rotate jobs and take more frequent breaks. People who have been away from work for 3 or more days may require acclimation.
Diet and life-style – Avoid large meals during work breaks because they increase circulatory load and metabolic rate. Adequate sleep; good diet and regular exercise reduce the risks of heat stroke. Abuse of alcohol or drugs increase the risks.

Cold Stress

With extreme cold temperatures, workers face the risk of hypothermia, even to the point of frostbite. Cold temperatures are aggravated by wet clothing, wind or contact with metal machine controls. Older workers or workers with circulatory problems require special precautionary protection against cold injury (e.g. extra insulating clothing, reduction in the exposure period). Some diseases and some medications reduce tolerance to work in cold environments. A physician should be consulted for workers who are at an elevated risk of cold stress.

Hypothermia occurs as the body chills and its core temperature drops. It generally reduces mental alertness, rational decision-making, and manual dexterity – each of which can lead to accidents or unsafe behaviors. As body temperature lowers further, loss of consciousness is possible with the threat of fatality. Symptoms of hypothermia include shivering, minor frostbite (frostnip), the feeling of excessive fatigue, drowsiness, irritability, or euphoria. If these symptoms arise, the person should be moved to a warm area and wet clothing removed. Modest external warming should be provided using external heat packs or blankets. If the person is conscious, he should drink warm, sweet fluids. The person should be transported to the hospital. A person experiencing hypothermia should not be given drinks with alcohol or caffeine (coffee, tea, or hot chocolate).

Frostbite involves freezing into deep layers of skin and tissue. Typically the fingers, hands, toes, feet, ears, and nose are at the greatest risk. The skin appears waxy, unusually pale or dark and becomes hard and numb, or blisters form. With frostbite, it is necessary to address freezing of damaged tissues. The tissue should be treated as a burn and the affected area should not be rubbed.

Practices that reduce the risk of cold stress, hypothermia and frostbite include:

Where clothing may become wet on the job site, for light work, the outer layer of clothing should be impermeable to water. For heavier work, the outer layer should be water repellent and changed as it becomes wetted.
More frequent indoor breaks may be needed when work is performed continuously in the cold, below 19.4°F (-7°C) (or equivalent wind chill temperature).
Work should be planned to minimize sitting still or standing still for long periods.
Protect the worker from drafts to the greatest extent possible. The cooling effect of the wind should be reduced by shielding the work area or by wearing an easily removable windbreak garment.
Do not use unprotected metal chair seats. When working outside and using tools or machine controls, to prevent contact frostbite, workers should wear anti-contact gloves. If the air temperature is 0°F or below, wear mittens or gloves. Machine controls and tools should be designed for handling without needing to remove the mittens.
Dehydration can occur in a cold environment and may increase the susceptibility of the worker to injury due to a change in blood flow to the extremities. Warm sweet drinks and soups should be consumed to provide caloric intake and fluids. Consumption of coffee and other caffeinated beverages should be limited.

Exposure to Sunlight – UV Radiation

Exposure to sunlight is a health concern because ultraviolet (UV ) radiation increases the risks of skin cancer. Be particularly careful in the sun if you burn easily. Employees who regularly work outside should frequently check their body for early signs of skin cancer, especially for a spot on the skin that is changing in size, shape, or color during a period of one month to two years. If such symptoms appear, a health care professional should be seen immediately as skin cancers detected early can almost always be cured.

When working outside, to protect against ultraviolet rays of the sun, workers should:

Wear tightly-woven clothing.
Wear a sunscreen with SPF of at least 15.
Wear a wide brim hat that shades the back of the neck (not a baseball cap).
Wear UV-absorbent sunglasses to block 99 – 100% of UVA and UVB radiation.
Limit exposure to the sun between 10 AM and 4 PM.
Wear special safety goggles or UV-absorbent sunglasses to protect the eyes, including from UV radiation reflected from snow in the winter.