Non-ionizing radiation refers to electromagnetic radiation that does not have sufficient energy to ionize (remove electrons from) atoms or molecules. Instead, the energy is converted to heat and can damage tissue. There are many sources of non-ionizing radiation (NIR) at SF State, ranging from common consumer technology to devices used in research and the arts. Very few of these will actually pose a significant risk during use.
Sources of NIR
Sources of non-ionizing radiation that pose a risk are generally associated with a specific research project or only pose a risk during maintenance activities when existing controls are removed or modified.
- Nuclear magnetic resonance (NMR)
- Microwave ovens (labs)
- UV lamps
- Induction heaters (heating metals)
- Fluorescence microscopes
- Infrared (IR) spectrometers
- Lasers and more
Sources of non-ionizing radiation include everyday things such as:
- Tanning beds
- Sunlight
- Microwave ovens (kitchens)
- Wireless devices such as: cell phones. cell phone towers. Wi-Fi equipment
- Lighting products such as: LED lights. incandescent light bulbs. Fluorescent tubes
- Power lines and household wiring
- Hand-held lasers and laser pointers
SF State has a Non-Ionizing Radiation Committee (NIRC) that currently oversees the use of Class 3B and 4 lasers, but will address other NIR issues as needed. Contact EH&S for help with non-ionizing radiation sources. Minimizing the risk of over-exposure usually involves engineering solutions, signage, and following safe operating procedures. EH&S provides the services listed below:
- Training
- Evaluation of NIR sources
- Design review
- Consultation
Types of NIR
The different visible frequencies of the electromagnetic (EM) spectrum are "seen" by our eyes as different colors. Good lighting is conducive to increased production, and may help prevent incidents related to poor lighting conditions. Excessive visible radiation can damage the eyes and skin.
Lasers typically emit optical (UV, visible light, IR) radiations and are primarily an eye and skin hazard. Common lasers include CO2 IR laser; helium - neon, neodymium YAG, and ruby visible lasers, and the Nitrogen UV laser.
For information on the university's Laser Safety Program, visit the Laser Safety web page.
Ultraviolet radiation is a natural part of solar radiation, and also is released by black lights, tanning beds, and electric arc lighting. UV light reaching the earth's surface is non-ionizing. Normal everyday levels of UV radiation can be helpful, and produce vitamin D. The World Health Organization (WHO) recommends 5 to 15 minutes of sun exposure 2 to 3 times a week.
Too much UV radiation can cause skin burns, premature aging of the skin, eye damage, and skin cancer. The majority of skin cancers are caused by exposure to ultraviolet radiation.
Laboratories using ultraviolet (UV) equipment (e.g., transilluminator, gel documentation equipment, biosafety cabinet, crosslinker or curing light) should be provided with the following personal protective equipment (PPE) if the hazard cannot be engineered out:
- Appropriately rated safety glasses, goggles, or face shields
- Long-sleeved clothing to protect arms, hands and neck
- Gloves
The skin and eyes absorb infrared radiation (IR) as heat. Workers normally notice excessive exposure through heat sensation and pain. Sources of IR radiation include furnaces, heat lamps, and IR lasers.
Static magnetic fields are created from a fixed magnet or magnetic flux resulting from the flow of electric current. The greater the current, the stronger the magnetic field. Examples of instruments that generate large static magnetic fields are nuclear magnetic resonance (NMR) spectrometers and magnetic resonance imaging (MRI) scanners.
An object made of ferrous materials, such as steel, can become a projectile when it is pulled rapidly toward the strong magnet and result in a hazardous situation or injury. Therefore, objects such as keys, scissors, knives, wrenches, oxygen cylinders and other ferromagnetic objects must be prohibited from the immediate vicinity of the magnet. In addition, anyone wearing cardiac pacemakers, metallic implants, and other electronic or electromagnetic prosthetic devices should be kept away from strong electromagnetic sources.
Superconducting magnets use liquid nitrogen and liquid helium coolants, to maintain the magnet coils in their superconductive state. Hence, precautions associated with the use of such cryogenic liquids must be observed as well.
Microwave radiation (MW) is absorbed near the skin. At high enough intensities exposure will damage tissue through heating. Sources of MW radiation include radio emitters and cell phones.
EH&S does not survey household-type microwave ovens for leakage as most microwaves have intact doors and door seals that do not produce excessive microwave leakage.
The following control measures or care must be taken while using microwaves:
- Do not use a metal stirrer or plastic-coated magnetic stirrer bars, aluminum foil wires, cables in a microwave oven.
- Do not attempt to heat flammable liquids or solids, hazardous substances or radioactive material in a microwave oven.
- Do not heat sealed containers; pressure can build up can cause an explosion either in the oven or shortly after removal.
- Do not overheat liquids in a microwave oven. It is possible to raise water to a temperature greater than the normal boiling point; when this occurs, any disturbance to the liquid can trigger violent boiling that could result in severe burns.
- No unauthorized repairs on a microwave oven. If a unit is suspected to be malfunctioning, disconnect it from the power supply, remove it from service and label it with an appropriate tag while awaiting repair or disposal. Any irreparable microwave oven should be rendered inoperable by removal of the plug and cord before disposal.
Radio frequency (RF) radiation may be absorbed throughout the body. At high enough intensities RF will damage tissue through heating. Sources of RF radiation include radio emitters and cell phones.
Radiofrequency-generating devices are most commonly used for telecommunication purposes (e.g., mobile phones, base stations, Wi-Fi, radio transmitters or wireless antennas).
Extremely Low Frequency (ELF) radiation at 60 HZ is produced by power lines, electrical wiring, and electrical equipment. Common sources of intense exposure include ELF induction furnaces and high-voltage power lines.