Physical Agents

The Electromagnetic Spectrum

The electromagnetic (EM) spectrum is the range of all types of EM radiation. Radiation is energy that travels and spreads out as it goes – the visible light that comes from a lamp in your house and the radio waves that come from a radio station are two types of electromagnetic radiation. The other types of EM radiation that make up the electromagnetic spectrum are microwaves, infrared light, ultraviolet light, X-rays and gamma-rays.

You know more about the electromagnetic spectrum than you may think. The image below shows where you might encounter each portion of the EM spectrum in your day-to-day life.

Is a radio wave the same as a gamma ray?

Are radio waves completely different physical objects than gamma-rays? They are produced in different processes and are detected in different ways, but they are not fundamentally different. Radio waves, gamma-rays, visible light, and all the other parts of the electromagnetic spectrum are electromagnetic radiation.

Electromagnetic radiation can be described in terms of a stream of mass-less particles, called photons, each traveling in a wave-like pattern at the speed of light. Each photon contains a certain amount of energy. The different types of radiation are defined by the the amount of energy found in the photons. Radio waves have photons with low energies, microwave photons have a little more energy than radio waves, infrared photons have still more, then visible, ultraviolet, X-rays, and, the most energetic of all, gamma-rays.

Measuring electromagnetic radiation

Electromagnetic radiation can be expressed in terms of energy, wavelength, or frequency. Frequency is measured in cycles per second, or Hertz. Wavelength is measured in meters. Energy is measured in electron volts. Each of these three quantities for describing EM radiation are related to each other in a precise mathematical way. But why have three ways of describing things, each with a different set of physical units?

The short answer is that scientists don’t like to use numbers any bigger or smaller than they have to. It is much easier to say or write “two kilometers” than “two thousand meters.” Generally, scientists use whatever units are easiest for the type of EM radiation they work with.

Astronomers who study radio waves tend to use wavelengths or frequencies. Most of the radio part of the EM spectrum falls in the range from about 1 cm to 1 km, which is 30 gigahertz (GHz) to 300 kilohertz (kHz) in frequencies. The radio is a very broad part of the EM spectrum.

Infrared and optical astronomers generally use wavelength. Infrared astronomers use microns (millionths of a meter) for wavelengths, so their part of the EM spectrum falls in the range of 1 to 100 microns. Optical astronomers use both angstroms (0.00000001 cm, or 10^-8 cm) and nanometers (0.0000001 cm, or 10^-7 cm). Using nanometers, violet, blue, green, yellow, orange, and red light have wavelengths between 400 and 700 nanometers. (This range is just a tiny part of the entire EM spectrum, so the light our eyes can see is just a little fraction of all the EM radiation around us.)

The wavelengths of ultraviolet, X-ray, and gamma-ray regions of the EM spectrum are very small. Instead of using wavelengths, astronomers that study these portions of the EM spectrum usually refer to these photons by their energies, measured in electron volts (eV). Ultraviolet radiation falls in the range from a few electron volts to about 100 eV. X-ray photons have energies in the range 100 eV to 100,000 eV (or 100 keV). Gamma-rays then are all the photons with energies greater than 100 keV.

Why do we put telescopes in orbit?

Most electromagnetic radiation from space is unable to reach the surface of the Earth. Radio frequencies, visible light and some ultraviolet light makes it to sea level. Astronomers can observe some infrared wavelengths by putting telescopes on mountain tops. Balloon experiments can reach 35 km above the surface and can operate for months. Rocket flights can take instruments all the way above the Earth’s atmosphere, but only for a few minutes before they fall back to Earth.^[1]

What is noise-induced hearing loss?

Every day, we experience sound in our environment, such as the sounds from television and radio, household appliances, and traffic. Normally, these sounds are at safe levels that don’t damage our hearing. But sounds can be harmful when they are too loud, even for a brief time, or when they are both loud and long-lasting. These sounds can damage sensitive structures in the inner ear and cause noise-induced hearing loss (NIHL).

NIHL can be immediate or it can take a long time to be noticeable. It can be temporary or permanent, and it can affect one ear or both ears. Even if you can’t tell that you are damaging your hearing, you could have trouble hearing in the future, such as not being able to understand other people when they talk, especially on the phone or in a noisy room. Regardless of how it might affect you, one thing is certain: noise-induced hearing loss is something you can prevent.

Who is affected by NIHL?

Exposure to harmful noise can happen at any age. People of all ages, including children, teens, young adults, and older people, can develop NIHL. Based on a 2011-2012 CDC study involving hearing tests and interviews with participants, at least 10 million adults (6 percent) in the U.S. under age 70—and perhaps as many as 40 million adults (24 percent)—have features of their hearing test that suggest hearing loss in one or both ears from exposure to loud noise. Researchers have also estimated that as many as 17 percent of teens (ages 12 to 19) have features of their hearing test suggestive of NIHL in one or both ears (Pediatrics 2011

), based on data from 2005-2006.

What causes NIHL?

NIHL can be caused by a one-time exposure to an intense “impulse” sound, such as an explosion, or by continuous exposure to loud sounds over an extended period of time, such as noise generated in a woodworking shop.

Recreational activities that can put you at risk for NIHL include target shooting and hunting, snowmobile riding, listening to MP3 players at high volume through earbuds or headphones, playing in a band, and attending loud concerts. Harmful noises at home may come from sources including lawnmowers, leaf blowers, and woodworking tools.

Sound is measured in units called decibels. Sounds at or below 70 A-weighted decibels (dBA), even after long exposure, are unlikely to cause hearing loss. However, long or repeated exposure to sounds at or above 85 dBA can cause hearing loss. The louder the sound, the shorter the amount of time it takes for NIHL to happen.

Here are the average decibel ratings of some familiar sounds:

• Normal conversation
  60-70 dBA
• Movie theater
  74-104 dBA
• Motorcyles and dirt bikes
  80-110 dBA
• Music through headphones at maximum volume, sporting events, and concerts
  94-110 dBA
• Sirens
  110-129 dBA
• Fireworks show
  140-160 dBA

Your distance from the source of the sound and the length of time you are exposed to the sound are also important factors in protecting your hearing. A good rule of thumb is to avoid noises that are too loud, too close, or last too long.

How can noise damage our hearing? (Graphic ^[2]

To understand how loud noises can damage our hearing, we have to understand how we hear. Hearing depends on a series of events that change sound waves in the air into electrical signals. Our auditory nerve then carries these signals to the brain through a complex series of steps.

Image

1. Sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum.
2. The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones are called the malleus, incus, and stapes.
3. The bones in the middle ear couple the sound vibrations from the air to fluid vibrations in the cochlea of the inner ear, which is shaped like a snail and filled with fluid. An elastic partition runs from the beginning to the end of the cochlea, splitting it into an upper and lower part. This partition is called the basilar membrane because it serves as the base, or ground floor, on which key hearing structures sit.
4. Once the vibrations cause the fluid inside the cochlea to ripple, a traveling wave forms along the basilar membrane. Hair cells—sensory cells sitting on top of the basilar membrane—ride the wave.
5. As the hair cells move up and down, microscopic hair-like projections (known as stereocilia) that perch on top of the hair cells bump against an overlying structure and bend. Bending causes pore-like channels, which are at the tips of the stereocilia, to open up. When that happens, chemicals rush into the cell, creating an electrical signal.
6. The auditory nerve carries this electrical signal to the brain, which translates it into a sound that we recognize and understand.

Most NIHL is caused by the damage and eventual death of these hair cells. Unlike bird and amphibian hair cells, human hair cells don’t grow back. They are gone for good.

What are the effects and signs of NIHL?

When you are exposed to loud noise over a long period of time, you may slowly start to lose your hearing. Because the damage from noise exposure is usually gradual, you might not notice it, or you might ignore the signs of hearing loss until they become more pronounced. Over time, sounds may become distorted or muffled, and you might find it difficult to understand other people when they talk or have to turn up the volume on the television. The damage from NIHL, combined with aging, can lead to hearing loss severe enough that you need hearing aids to magnify the sounds around you to help you hear, communicate, and participate more fully in daily activities.

NIHL can also be caused by extremely loud bursts of sound, such as gunshots or explosions, which can rupture the eardrum or damage the bones in the middle ear. This kind of NIHL can be immediate and permanent.

Loud noise exposure can also cause tinnitus—a ringing, buzzing, or roaring in the ears or head. Tinnitus may subside over time, but can sometimes continue constantly or occasionally throughout a person’s life. Hearing loss and tinnitus can occur in one or both ears.

Sometimes exposure to impulse or continuous loud noise causes a temporary hearing loss that disappears 16 to 48 hours later. Recent research suggests, however, that although the loss of hearing seems to disappear, there may be residual long-term damage to your hearing.

Can NIHL be prevented?

NIHL is the only type of hearing loss that is completely preventable. If you understand the hazards of noise and how to practice good hearing health, you can protect your hearing for life. Here’s how:

• Know which noises can cause damage.
• Wear earplugs or other protective devices when involved in a loud activity (activity-specific earplugs and earmuffs are available at hardware and sporting goods stores).
• If you can’t reduce the noise or protect yourself from it, move away from it.
• Be alert to hazardous noises in the environment.
• Protect the ears of children who are too young to protect their own.
• Make family, friends, and colleagues aware of the hazards of noise.
• Have your hearing tested if you think you might have hearing loss.

What research is being done on NIHL?

The National Institute on Deafness and Other Communication Disorders (NIDCD) supports research on the causes, diagnosis, treatment, and prevention of hearing loss. NIDCD- supported researchers have helped to identify some of the many genes important for hair-cell development and function and are using this knowledge to explore new treatments for hearing loss.

Researchers are also looking at the protective properties of supporting cells in the inner ear, which appear to be capable of lessening the damage to sensory hair cells upon exposure to noise.

The NIDCD sponsors It’s a Noisy Planet. Protect Their Hearing®, a national public education campaign to increase awareness among parents of preteens about the causes and prevention of NIHL. Armed with this information, parents, teachers, school nurses, and other adults can encourage children to adopt healthy hearing habits.^[3]

Cold Stress Guide

Anyone working in a cold environment may be at risk of cold stress. Some workers may be required to work outdoors in cold environments and for extended periods, for example, snow cleanup crews, sanitation workers, police officers and emergency response and recovery personnel, like firefighters, and emergency medical technicians. Cold stress can be encountered in these types of work environment. The following frequently asked questions will help workers understand what cold stress is, how it may affect their health and safety, and how it can be prevented.

How cold is too cold?

What constitutes extreme cold and its effects can vary across different areas of the country. In regions that are not used to winter weather, near freezing temperatures are considered “extreme cold.” A cold environment forces the body to work harder to maintain its temperature. Whenever temperatures drop below normal and wind speed increases, heat can leave your body more rapidly.  Cold stress is a factor of low temperature plus the wind speed plus the wetness of the individual.

Wind chill is the temperature your body feels when air temperature and wind speed are combined. For example, when the air temperature is 40°F, and the wind speed is 35 mph, the effect on the exposed skin is as if the air temperature was 28°F.

Cold stress occurs by driving down the skin temperature and eventually the internal body temperature (core temperature). This may lead to serious health problems, and may cause tissue damage, and possibly death.

What are the risk factors that contribute to cold stress?

Some of the risk factors that contribute to cold stress are:

• Wetness/dampness, dressing improperly, and exhaustion
• Predisposing health conditions such as hypertension, hypothyroidism, and diabetes
• Poor physical conditioning

How does the body react to cold conditions?

In a cold environment, most of the body’s energy is used to keep the internal core temperature warm. Over time, the body will begin to shift blood flow from the extremities (hands, feet, arms, and legs) and outer skin to the core (chest and abdomen). This shift allows the exposed skin and the extremities to cool rapidly and increases the risk of frostbite and hypothermia. Combine this scenario with exposure to a wet environment, and trench foot may also be a problem.

What are the most common cold induced illnesses/injuries?

• Hypothermia
• Frostbite
• Trench Foot

What is hypothermia?

Hypothermia occurs when body heat is lost faster than it can be replaced and the normal body temperature (98.6°F) drops to less than 95°F. Hypothermia is most likely at very cold temperatures, but it can occur even at cool temperatures (above 40°F), if a person becomes chilled from rain, sweat, or submersion in cold water.

What are the symptoms of hypothermia?

• Mild symptoms:
  • An exposed worker is alert.
  • He or she may begin to shiver and stomp the feet in order to generate heat.
• Moderate to Severe symptoms:
  • As the body temperature continues to fall, symptoms will worsen and shivering will stop.
  • The worker may lose coordination and fumble with items in the hand, become confused and disoriented
  • He or she may be unable to walk or stand, pupils become dilated, pulse and breathing become slowed, and loss of consciousness can occur. A person could die if help is not received immediately.

What can be done for a person suffering from hypothermia?

• Call 911 immediately in an emergency; otherwise seek medical assistance as soon as possible.
• Move the person to a warm, dry area.
• Remove wet clothes and replace with dry clothes, cover the body (including the head and neck) with layers of blankets; and with a vapor barrier (e.g. tarp, garbage bag). Do not cover the face.
• If medical help is more than 30 minutes away:
  • Give warm sweetened drinks if alert (no alcohol), to help increase the body temperature. Never try to give a drink to an unconscious person.
  • Place warm bottles or hot packs in armpits, sides of chest, and groin. Call 911 for additional rewarming instructions.
• If a person is not breathing or has no pulse:
  • Call 911 for emergency medical assistance immediately.
  • Treat the worker as per instructions for hypothermia, but be very careful and do not try to give an unconscious person fluids.
  • Check him/her for signs of breathing and for a pulse. Check for 60 seconds.
  • If after 60 seconds the affected worker is not breathing and does not have a pulse, trained workers may start rescue breaths for 3 minutes.
  • Recheck for breathing and pulse, check for 60 seconds.
  • If the worker is still not breathing and has no pulse, continue rescue breathing.
  • Only start chest compressions per the direction of the 911 operator or emergency medical services^*
  • Reassess patient’s physical status periodically.

^*Chest compression are recommended only if the patient will not receive medical care within 3 hours.

What is frostbite?

Frostbite is an injury to the body that is caused by freezing of the skin and underlying tissues. The lower the temperature, the more quickly frostbite will occur. Frostbite typically affects the extremities, particularly the feet and hands. Amputation may be required in severe cases.

What are the symptoms of frostbite?

• Reddened skin develops gray/white patches.
• Numbness in the affected part.
• Feels firm or hard.
• Blisters may occur in the affected part, in severe cases.

What can be done for a person suffering from frostbite?

• Follow the recommendations described above for hypothermia.
• Do not rub the affected area to warm it because this action can cause more damage.
• Do not apply snow/water. Do not break blisters.
• Loosely cover and protect the area from contact.
• Do not try to rewarm the frostbitten area before getting medical help; for example, do not place in warm water. If a frostbitten area is rewarmed and gets frozen again, more tissue damage will occur. It is safer for the frostbitten area to be rewarmed by medical professionals.
• Give warm sweetened drinks, if the person is alert. Avoid drinks with alcohol.

What is immersion/trench foot?

Trench Foot or immersion foot is caused by prolonged exposure to wet and cold temperatures. It can occur at temperatures as high as 60°F if the feet are constantly wet. Non-freezing injury occurs because wet feet lose heat 25-times faster than dry feet. To prevent heat loss, the body constricts the blood vessels to shut down circulation in the feet. The skin tissue begins to die because of a lack of oxygen and nutrients and due to the buildup of toxic products.

What are the symptoms of trench foot?

• Redness of the skin, swelling, numbness, blisters

What can be done for a person suffering from immersion foot?

• Call 911 immediately in an emergency; otherwise seek medical assistance as soon as possible.
• Remove the shoes, or boots, and wet socks.
• Dry the feet.

How can cold stress be prevented?

Although OSHA does not have a specific standard that covers working in cold environments, employers have a responsibility to provide workers with employment and a place of employment which are free from recognized hazards, including cold stress, which are causing or are likely to cause death or serious physical harm to them (Section 5(a)(1) of the Occupational Safety and Health Act of 1970). Employers should, therefore, train workers on the hazards of the job and safety measures to use, such as engineering controls and safe work practices, that will protect workers’ safety and health.

Employers should train workers on how to prevent and recognize cold stress illnesses and injuries and how to apply first aid treatment. Workers should be trained on the appropriate engineering controls, personal protective equipment and work practices to reduce the risk of cold stress.

Employers should provide engineering controls. For example, radiant heaters may be used to warm workers in outdoor security stations. If possible, shield work areas from drafts or wind to reduce wind chill.

Employers should use safe work practices. For example, it is easy to become dehydrated in cold weather. Employers therefore, can provide plenty of warm sweetened liquids to workers. Avoid alcoholic drinks. If possible, employers can schedule heavy work during the warmer part of the day. Employers can assign workers to tasks in pairs (buddy system), so that they can monitor each other for signs of cold stress. Workers can be allowed to interrupt their work, if they are extremely uncomfortable. Employers should give workers frequent breaks in warm areas. Acclimatize new workers and those returning after time away from work, by gradually increasing their workload, and allowing more frequent breaks in warm areas, as they build up a tolerance for working in the cold environment. Safety measures, such as these, should be incorporated into the relevant health and safety plan for the workplace.

Dressing properly is extremely important to preventing cold stress. The type of fabric worn also makes a difference. Cotton loses its insulation value when it becomes wet. Wool, silk and most synthetics, on the other hand, retain their insulation even when wet. The following are recommendations for working in cold environments:

• Wear at least three layers of loose fitting clothing. Layering provides better insulation. Do not wear tight fitting clothing.
  • An inner layer of wool, silk or synthetic to keep moisture away from the body.
  • A middle layer of wool or synthetic to provide insulation even when wet.
  • An outer wind and rain protection layer that allows some ventilation to prevent overheating.
• Wear a hat or hood to help keep your whole body warmer. Hats reduce the amount of body heat that escapes from your head.
• Use a knit mask to cover the face and mouth (if needed).
• Use insulated gloves to protect the hands (water resistant if necessary).
• Wear insulated and waterproof boots (or other footwear).

Safety Tips for Workers

• Your employer should ensure that you know the symptoms of cold stress.
• Monitor your physical condition and that of your coworkers.
• Dress properly for the cold.
• Stay dry in the cold because moisture or dampness, e.g. from sweating, can increase the rate of heat loss from the body.
• Keep extra clothing (including underwear) handy in case you get wet and need to change.
• Drink warm sweetened fluids (no alcohol).
• Use proper engineering controls, safe work practices, and personal protective equipment (PPE) provided by your employer.^[4]

Working in Outdoor and Indoor Heat Environments

Occupational risk factors for heat illness include heavy physical activity, warm or hot environmental conditions, lack of acclimatization, and wearing clothing that holds in body heat. (See also, personal risk factors, below.)

Hazardous heat exposure can occur indoors or outdoors, and can occur during any season if the conditions are right, not only during heat waves. The following is a list of some industries where workers have suffered heat-related illnesses.

Heat-Related Illnesses and First Aid

Several heat-related illnesses can affect workers. Some of the symptoms are non-specific. This means that when a worker is performing physical labor in a warm environment, any unusual symptom can be a sign of overheating.

Heat-Related Illness	Symptoms and Signs
Heat stroke	Confusion Slurred speech Unconsciousness Seizures Heavy sweating or hot, dry skin Very high body temperature Rapid heart rate
Heat exhaustion	Fatigue Irritability Thirst Nausea or vomiting Dizziness or lightheadedness Heavy sweating Elevated body temperature or fast heart rate
Heat cramps	Muscle spasms or pain Usually in legs, arms, or trunk
Heat syncope	Fainting Dizziness
Heat rash	Clusters of red bumps on skin Often appears on neck, upper chest, and skin folds
Rhabdomyolysis (muscle breakdown)	Muscle pain Dark urine or reduced urine output Weakness

Employers and workers should become familiar with the heat symptoms. When any of these symptoms is present, promptly provide first aid. Do not try to diagnose which illness is occurring. Diagnosis is often difficult because symptoms of multiple heat-related illnesses can occur together. Time is of the essence. These conditions can worsen quickly and result in fatalities.

When in doubt, cool the worker and call 911.

See below for further first aid recommendations.

First Aid

OSHA’s Medical Services and First Aid standard and the Medical Service and First Aid in Construction require the ready availability of first aid personnel and equipment. First aid for heat-related illness involves the following principles:

• Take the affected worker to a cooler area (e.g., shade or air conditioning).
• Cool the worker immediately. Use active cooling techniques such as:
  • Immerse the worker in cold water or an ice bath. Create the ice bath by placing all of the available ice into a large container with water, standard practice in sports. This is the best method to cool workers rapidly in an emergency.
  • Remove outer layers of clothing, especially heavy protective clothing.
  • Place ice or cold wet towels on the head, neck, trunk, armpits, and groin.
  • Use fans to circulate air around the worker.
• Never leave a worker with heat-related illness alone. The illness can rapidly become worse. Stay with the worker.
• When in doubt, call 911!

Confusion, slurred speech, or unconsciousness are signs of heat stroke. When these types of symptoms are present, call 911 immediately and cool the worker with ice or cold water until help arrives.

Workers who are new to working in warm environments are at increased risk of heat-related illness. See the Protecting New Workers section of this website for more details. Especially during a worker’s first few days, absolutely all symptoms should be taken seriously. Workers who develop symptoms should be allowed to stop working. They should receive evaluation for possible heat-related illness.

Outdoors	Indoors
Agriculture	Bakeries, kitchens, and laundries (sources with indoor heat-generating appliances)
Construction – especially, road, roofing, and other outdoor work	Electrical utilities (particularly boiler rooms)
Construction – roofing work	Fire Service
Landscaping	Iron and steel mills and foundries
Mail and package delivery	Manufacturing with hot local heat sources, like furnaces (e.g., paper products or concrete)
Oil and gas well operations	Warehousing

Heat-related illness is preventable, especially with management commitment to providing the most effective controls. An effective heat-related illness prevention program is incorporated in a broader safety and health program and aligns with OSHA’s Recommended Practices for Safety and Health Programs core elements.

Workers who have not spent time recently in warm or hot environments and/or being physically active will need time to build tolerance (acclimatize or, less frequently used, acclimate) to the heat. During their first few days in warm or hot environments, employers should encourage workers to:

• Consume adequate fluids (water and sport drinks)
• work shorter shifts,
• take frequent breaks, and
• quickly identify any heat illness symptoms.

Engineering controls such as air conditioning, with cooled air, and increased air flow, leading to increased evaporative cooling, can make the workplace safer. Other options for keeping body temperatures down in warm environments include making changes to workload and schedules. For example, empower supervisors and workers to slow down physical activity like reducing manual handling speeds or scheduling work for the morning or shorter shifts with frequent rest breaks in the shade or at least away from heat sources. Supervisors can encourage workers in warm environments to drink hydrating fluids. At a minimum, all supervisors and workers should receive training about heat-related symptoms and first aid.

Heat-related illnesses can have a substantial cost to workers and employers. Heat stress can cause fine motor performance (like rebar tying or keyboarding) to deteriorate even in acclimatized individuals. Heat illness can contribute to decreased performance, lost productivity due to illness and hospitalization, and possibly death. OSHA encourages water, rest, and shade as prevention as well as treatment for heat-related illness.

Occupational heat exposure is a combination of many factors. Body heat results from the equilibrium of heat gain, from internal work and outside addition, and heat loss, primarily from evaporative cooling, i.e., sweat evaporation. Contributors include:

• Physical activity
• Air temperature
• Humidity
• Sunlight
• Heat sources (e.g., ovens or furnaces, heat-absorbing roofs, and road surfaces)
• Air movement
• Clothing that hampers the body’s ability to lose excess heat, such as protective gear
• Individual/personal risk factors, (e.g., pre-existing health conditions and lifestyle)

Management should commit to considering all factors that contribute to body temperature increase when determining if a heat hazard is present in a workplace. Physical activity (workload) can be estimated using tables such as this one. Employers should also be aware of whether workers’ clothing increases risk.

In addition to a thermometer, use these resources to assess heat stress:

• Use an on-site wet bulb globe temperature (WBGT) meter – the most accurate way (Morris 2018) to measure environmental heat impact on body temperature. WBGT incorporates temperature, humidity, sunlight, and air movement into a single measurement. ^[5]

Ionizing radiation

Ionizing radiation is radiation with enough energy that to remove tightly bound electrons from the orbit of an atom, causing that atom to become charged or ionized.

Here we are concerned with only one type of radiation, ionizing radiation, which occurs in two forms: waves or particles.

There are several forms of electromagnetic radiation, which differ only in frequency and wavelength:

• heat waves
• radio waves
• infrared light
• visible light
• ultraviolet light
• X rays
• gamma rays.

Longer wavelength, lower frequency waves such as heat and radio have less energy than shorter wavelength, higher frequency waves like X and gamma rays. Not all electromagnetic (EM) radiation is ionizing. Only the high frequency portion of the electromagnetic spectrum, which includes X rays and gamma rays, is ionizing.