Carnegie Mellon University

Workplace Safety

Nobody is immune from being injured on the job. We have selected our most common types of injuries and developed programs for preventing them from happening. If you perform any of the jobs listed, take a few minutes to read the information. It may save you from a painful injury.

Employees who are required to enter OSHA-defined confined spaces must attend Confined Space Entry Training prior to making the entry.  Confined space rescuers must also complete a training. Conversely, those who have no need to enter a confined space are prohibited from doing so. Because of the serious nature of confined space accidents there are no exceptions to this rule.

OSHA defines a confined space as a space that:

  • Is large enough and so configured that an employee can enter and perform work, AND
  • Is not intended for continuous occupancy, AND
  • Has a limited or restricted means of entrance or egress.

In addition, if all three of these conditions exist and any of the following also are present or potentially present, a written entry permit must be obtained from EH&S prior to entry:

  • hazardous atmosphere, OR
  • material which could engulf an entrant
  • an internal configuration such that the entrant could be trapped or asphyxiated.

Determination of any space in question can be made by contacting EH&S.

All of us must be aware of the potential dangers associated with working in hot conditions. Although these conditions are obviously most prevalent in the summer, working in any hot environment, including an unventilated room, can also present some heat-related danger.

Pay attention to the following reminders:

HEAT STROKE occurs when the body's system of temperature regulation fails and body temperature rises to critical levels. This condition is caused by a combination of highly variable factors, and its occurrence is difficult to predict. Heat stroke is a medical emergency. The primary signs and symptoms of heat stroke are confusion; irrational behavior; loss of consciousness; convulsions; a lack of sweating (usually); hot, dry skin; and an abnormally high body temperature.  If body temperature is too high, it can cause death.

If an individual shows signs of possible heat stroke, professional medical treatment must be obtained immediately. The individual should be placed in a cool area and the outer clothing should be removed. The person's skin should be wetted and air movement around the worker should be increased to improve evaporative cooling until professional methods of cooling are initiated and the seriousness of the condition can be assessed. Fluids should be replaced as soon as possible. The medical outcome of an episode of heat stroke depends on the victim's physical fitness and the timing and effectiveness of first aid treatment.  Regardless of the person's protests, no individual suspected of being ill from heat stroke should be sent home alone or left unattended unless a physician has specifically approved such an order.  

HEAT EXHAUSTION The signs and symptoms of heat exhaustion are headache, nausea, vertigo, weakness, thirst, and giddiness. Fortunately, this condition responds readily to prompt treatment. Heat exhaustion should not be dismissed lightly, however, for several reasons. One is that the fainting associated with heat exhaustion can be dangerous because the victim may be operating machinery when fainting occurs; moreover, the victim may be injured when he or she faints. Also, the signs and symptoms seen in heat exhaustion are similar to those of heat stroke, a medical emergency.  Anyone suffering from heat exhaustion should be removed from the hot environment and given fluid replacement. They should also be encouraged to get adequate rest.

HEAT CRAMPS have been attributed to an electrolyte imbalance caused by sweating. It is important to understand that cramps can be caused by both too much and too little salt, and they appear to be directly related to a lack of water replenishment. Thirst cannot be relied on as a guide to the need for water; instead, water or commercially available carbohydrate-electrolyte replacement liquids (e.g., Gatorade) must be taken every 15 to 20 minutes in hot environments.

HEAT COLLAPSE ("Fainting").  In heat collapse, the brain does not receive enough oxygen because blood pools in the extremities. As a result, the exposed individual may lose consciousness. This reaction is similar to that of heat exhaustion and does not affect the body's heat balance. However, the onset of heat collapse is rapid and unpredictable. To prevent heat collapse, the worker should gradually become acclimatized to the hot environment.

HEAT RASHES are the most common problem in hot work environments.  Prickly heat is manifested as a rash and usually appears in areas where the clothing is restrictive. As sweating increases, the rash gives rise to a prickling sensation. Prickly heat occurs in skin that is persistently wetted by unevaporated sweat, and heat rash papules may become infected if they are not treated. In most cases, heat rashes will disappear when the affected individual returns to a cool environment.

HEAT FATIGUE. A factor that predisposes an individual to heat fatigue is lack of acclimatization. The use of a program of acclimatization and training for work in hot environments is advisable. The signs and symptoms of heat fatigue include impaired performance of skilled sensorimotor, mental, or vigilance jobs. There is no treatment for heat fatigue except to remove the heat stress before a more serious heat-related condition develops.


  • Ventilation, air cooling, fans, shielding, and insulation are the five major types of engineering controls used to reduce heat stress in hot work environments. Heat reduction can also be achieved by using power assists and tools that reduce the physical demands placed on an individual.
  • The human body can adapt to heat exposure to some extent.  After a period of acclimatization, the same activity will produce fewer cardiovascular demands. The individual will sweat more efficiently (causing better evaporative cooling), and thus will more easily be able to maintain normal body temperatures.
  • Replace fluids.  Cool (50°-60°F) water or any cool liquid (except alcoholic beverages, which actually have an undesirable affect on heat illnesses) should be kept available.  Drink small amounts frequently, e.g., one cup every 20 minutes.  Although some commercial replacement drinks contain salt, this is not necessary for acclimatized individuals because most people add enough salt to their summer diets.     
  • Hot jobs should be scheduled for the cooler part of the day, and routine maintenance and repair work should be scheduled for the cooler seasons of the year, when practical.
  • Anyone who works in conditions that increase the risk of heat stress should work within sight of someone else.
  • Each should monitor the other to ensure that nobody develops symptoms without someone knowing it.
  • Reduce the physical demands of the job, where possible.  Avoid digging, excessive lifting, etc. in the hot part of the day.
  • Have a recovery area where you can go to cool down.  If air conditioning is not available, try to get into a shady or cool area.  Breaks should be more frequent in hot weather.
  • Know the symptoms of heat related illnesses, and know how to respond.
  • Certain prescription drugs can exaggerate the effects of heat.  If you are taking a prescription medication, ask your doctor if it will contribute to the danger of working in the heat, and if so, what precautions you should take.

Nearly everyone is called on to use a ladder at some time. EH&S offers ladder safety and ladder & scaffolding safety training courses, which are recommended for anyone using a ladder in the course of their job. For others, the following guidelines should prove useful any time you find yourself needing to use a ladder.

  • Inspect ladders before using (make sure there are no breaks or cracks, all components must be in good working condition, no oil or grease on side rails or steps, no frayed or worn ropes, movable parts operate freely, no excessive wear, rungs securely attached to siderails, and are you using the proper ladder for the job?)
  • Before using a ladder, consider any external hazards: overhead obstructions, presence of electrical equipment, congested area, uneven surfaces, weather conditions, etc.
  • Never use a ladder that is too long or too short for what you are going to work on, and NEVER stand on a swivel chair, stool, desk, or other object when you need to reach something. Check the ladder’s load limits before putting it into service. Use this table to interpret the ladder rating that will be marked on the ladder somewhere:


Category Weight Limit, Pounds Rating
Type I-AA 375 Special Duty
Type I-A 300 Heavy Duty Industrial
Type I 250 Heavy Duty
Type II 225 Medium Duty
Type III 200 Light Duty

Only Types I, I-A, or I-AA are to be used at CMU

  • Do not use ladders as a brace, platform, scaffold, plank, or lever, and do not use the rungs for storage.
  • Never use a metal ladder near electrical sources, don’t use step ladders as straight ladders (i.e., leaned against the wall), and don’t tie ladders together to make a longer ladder.
  • If you have to use a ladder near a doorway, take one or more of these precautionary steps to make sure nobody comes through the door and knocks you from the ladder: lock the door, put up barricades, secure the ladder, and/or have somebody stand watch to warn others that a ladder is in use.
  • Set up straight ladders using the 4 to 1 rule: 1 foot from the wall for every 4 feet of the ladder’s working length.
  • When using a stepladder, open it fully, place it on a solid surface, and make sure the spreaders are locked into position. Do not stand on the top two rails, and never stand on the back section.

Anyone who works with equipment or machinery where there is a risk of injury due to an unexpected startup, energization, or release of stored energy must follow lockout/tagout procedures.

Types of energy that need to be dissipated and/or restrained by repositioning, blocking, bleeding, etc., include but are not limited to:

  • Electricity
  • Hydraulic
  • Pneumatic
  • Air
  • Gas
  • Steam
  • Water pressure
  • Gravity
  • Springs

Machine guards are your first line of defense against injuries caused by the operation of any kind of machinery.  OSHA regulations require guarding anywhere there is a danger of having any body part come in contact with a moving part.  

There are five general types of safeguards that are permitted to be used:

  1. Location - If a piece of equipment is located so that it is impossible to come in contact with it, or for someone to be contacted by any part of the process (e.g., splashing) no physical guarding is necessary.  An example of this would be an exhaust fan mounted in an outside wall 15' above floor level and out of reach of employees.
  2. Guards - These are physical barriers that prevent contact.  They are the most common type of protection we have at CMU, and we have them in nearly all our mechanical rooms.  Examples of these are guards over pump couplings, motors, belt drives, etc.
  3. Devices - Devices limit or prevent access to the hazardous area.  Examples of devices are photocells (sometimes called "electric eyes") that stop a machine if your hand enters a sensing field, or an interlock that requires all components to be in assigned positions before a machine will operate.
  4. Automated feeders and ejectors - These are normally found only in manufacturing operations.  They are designed to automatically feed stock into a machine without requiring the operator to place his hands into a dangerous position.  Punch presses use this type of guarding.
  5. Miscellaneous aids - Examples of these are shields to prevent sparks or chips from striking people in the immediate area, holding tools that an operator can use to keep his hands out of the way of moving parts, or even a rope barrier (often called an awareness barrier) that keeps you away from the machine.

Guards must be durable and secured or anchored so that they will not move during operation, but they have to be easy to remove for maintenance.  They are not permitted to create a hazard themselves.  An example of such a hazard would be a guard that is so large that it forces anyone walking past to take a more dangerous route.

The moving parts of any machine present a potential for severe injury.  Amputations, fractures, lacerations, or crushing injuries are all too common, and in the presence of large moving parts, not often found here at CMU fortunately, people have been pulled into the machinery and suffered fatal injuries.  Understanding the purpose and importance of machine guarding is important to anyone working around even the smallest of moving parts, such as a belt pulley.

If you take a guard off a piece of equipment to perform maintenance, be sure to replace it.  Often our inspections find guards sitting on the floor beside the piece of equipment they are meant to guard.  Having them beside the equipment, or even nearby, provides zero protection.  Guards must be in place to be effective.  Always replace guards that you remove to perform a repair or maintenance.  

The use of mechanical lifting equipment is the best way to minimize stress on the back.  A second choice is to push the load. Sometimes however, neither of these options is practical, so it is important that you know how to lift properly.

Always size up the load before you lift it.  Test it by lifting one of the corners to get an idea of its weight.  It may be necessary to get someone to help you, particularly if the object's shape is irregular, which will result in an awkward lift.

Before you actually make the lift, plan your route ahead of time.  Make sure there are no stumbling hazards where you will be walking, and that you will have a clear place to set the load down.  Check for good solid footing, especially if the surface is wet, greasy, muddy, or snow or ice covered, or if housekeeping is poor.

The most important rule when lifting is to bend at your knees. Center yourself over the load and maintain a good firm grip, then lift straight up. Never twist and turn while carrying an object.  If you have to turn, move your feet rather than turning at the waist. 

Once you've lifted and moved the load, at some point it will be necessary to set it down.  Doing this properly is just as important as picking it up.  Bend at the knees and lower the load slowly and smoothly.  

When you have to lift something, break it down into smaller loads if you can.  

If you should happen to lose your grip while lifting or carrying something, let it fall.  

Did you know?

  • Slips happen when there is too little friction between your feet and the ground.
  • Trips happen when something halts your motion.
  • Falls happen when your body is in an unstable position.

Prevent slips, trips and falls by:

  • Keeping your work areas and walkways clean
  • Keeping areas well lit so you can see where you are going
  • Wearing shoes appropriate for weather conditions
  • Using hand railings when walking up and down the stairs

Reporting damaged walkways and steps to Facilities Management Services -

  • Only tools and equipment which are in good condition may be used.
  • Tools shall only be used for the purpose for which they were designed.
  • Employees shall make frequent inspections of tools and equipment, and immediately remove from service any items found defective. The following are examples of the types of defects which should be looked for:
    • Split, broken, cracked, or splintered wooden handles.
    • Mushroomed heads on chisels or impact drills.
    • Wrench jaws which slip or do not hold.
    • Frayed cords, damaged or modified grounding plugs, or broken insulation
      • on electrical tools.
    • Rounded edges on sharp-edged tools.
    • Dull cutting tools.
  • When using hand tools, the employee shall place himself in such a position that he will avoid injury if the tool slips.
  • Only soft faced hammers (brass, plastic, rubber, or similar materials) shall be used on highly tempered steel tools such as cold chisels, star drills, etc. Proper eye protection must be worn when performing such an operation.
  • Files, rasps, and other tools having sharp tangs shall be equipped with approved handles.
  • Tools which are not in use shall be placed where they will not present a tripping or stumbling hazard.
  • Pointed tools shall never be carried edge or point up in pockets.
  • Tools shall not be thrown from one worker to another, or to another working location.
  • Extensions shall not be used on wrenches to gain leverage unless the wrench is designed to be used in such a fashion.
  • When cutting wire or any other material under tension, the material being cut shall be secured to prevent the ends from snapping free.
  • All power tools must be properly grounded before their use.
  • Gloves shall not be worn when operating lathes, drill presses, power saws, or similar equipment. Loose clothing must not be worn and long sleeves should be rolled up prior to operation.
  • Hooks, brushes, vacuums, or special tools shall be used to remove dust or chips. Compressed air shall not be used.
  • All machinery must be turned off when unattended.
  • Maintenance, repairs, adjustments, and measurements must not be made while saws, lathes, grinders, and similar equipment are in operation.
  • Compressed air shall never be used to dust off clothing, or be directed toward another person.
  • Sawblades, gears, sprockets, chains, shafts, pulleys, belts, and similar apparatus shall not be operated without the proper guarding.
  • Safety glasses, goggles, or face shields shall be worn when operating power tools.