A physical hazard is any environmental factor or agent that can cause injury or harm through its physical properties. These hazards are not biological or chemical, but relate instead to the transfer of energy, whether through contact, movement, or non-contact transmission. Understanding these agents is the foundation of safety management, as they are prevalent in both daily life and industrial settings.
Mechanical and Kinetic Hazards
Mechanical and kinetic hazards stem from the potential for injury involving moving parts, machinery, or the uncontrolled release of stored energy. The danger arises from the transfer of kinetic energy to the human body through mechanisms like impact, crushing, cutting, or shearing against moving or stationary components. The severity of the injury from a moving object is directly related to its mass and velocity, which determine the amount of kinetic energy transferred upon impact.
A significant concern involves pinch points, where two moving parts come together, posing a risk of trapping a limb or finger. Crushing hazards are common with heavy equipment, such as when an object falls or a body part is caught between two converging surfaces.
Cutting and shearing hazards involve objects with sharp edges or parts that slide past each other, like the blades on industrial shears. Even seemingly stable objects can pose a hazard, such as an improperly secured stack of materials that could fall. Similarly, a pressurized system, like a hose or tank, stores potential energy that, upon sudden failure, releases kinetic energy in the form of rapidly flying debris.
Electrical Hazards
Electrical hazards involve uncontrolled electrical current, resulting in injury through shock, arc flash, or electrocution. An electrical shock occurs when a person becomes part of an electrical circuit. The severity is determined by the amount of current, the path it takes through the body, and the duration of exposure.
Even relatively low currents can be dangerous; for instance, 0.2 amps passing through the chest for one second can cause ventricular fibrillation. Faulty wiring, improper grounding, or damaged insulation are common sources that create a pathway for current to travel through a person’s body.
The arc flash is a massive release of electrical energy into the air due to a fault, such as a short circuit. Unlike a shock, the arc flash is primarily a thermal and explosive event where the air itself becomes the conductor. Temperatures in an arc flash event can reach up to 35,000 degrees Fahrenheit. This intense heat causes severe burns, while the accompanying concussive pressure wave can cause internal trauma and the propulsion of molten metal and shrapnel.
Thermal Hazards
Thermal hazards are risks associated with exposure to temperature extremes that exceed the body’s ability to maintain its core temperature. The body’s thermoregulatory system works to balance heat gain and heat loss, but it can be overwhelmed by ambient or contact temperature. These hazards fall into two main categories: high-temperature and low-temperature risks.
High-temperature hazards include contact burns from hot surfaces, steam, or fire, which cause tissue damage through direct thermal energy transfer. Exposure to high ambient temperatures, often exacerbated by humidity, can lead to heat-related illnesses such as heat stress, heat exhaustion, and heatstroke. Heatstroke represents a medical emergency where the core temperature rises above 104°F (40°C), leading to potential organ damage and failure.
Conversely, low-temperature hazards cause the body to lose heat faster than it can be generated, leading to hypothermia. Hypothermia occurs when the body’s core temperature drops below 95°F (35°C). Cold stress can be intensified by wind chill or dampness, forcing the body to restrict blood flow to the extremities to conserve heat, which can result in localized tissue damage like frostbite.
Radiation Hazards
Radiation hazards involve the transmission of energy through waves or particles. These hazards are separated into two groups based on the energy of the radiation and its biological effect. The first type is ionizing radiation, which includes X-rays, gamma rays, and alpha and beta particles.
Ionizing radiation possesses sufficient energy to knock electrons from atoms, a process called ionization, which damages the DNA within living cells. This cellular damage can lead to acute effects like radiation sickness, or long-term chronic effects such as an increased risk of cancer.
The second type is non-ionizing radiation, which has lower energy and includes forms like ultraviolet (UV) light, microwaves, lasers, and radiofrequency waves. This type of radiation does not possess enough energy to ionize atoms, but it primarily causes harm through thermal effects. Prolonged exposure to non-ionizing UV light can also cause photochemical damage, such as sunburn and an increased risk of skin cancer.