What are safety glasses made of?
Why risk losing precious eyesight when wearing safety glasses or protective goggles can keep your eyes safe for a lifetime of good vision?
According to Prevent Blindness America, each year, more than 700,000 Americans injure their eyes at work, and another 125,000 injure their eyes at home. More than 40,000 American children and adults suffer eye injuries during sports, while many thousands more eye injuries go unreported.
Because experts say proper protective eyewear could prevent up to 90 per cent of all eye injuries, you might want to learn more about the safety glasses and goggles that suit your lifestyle best.
How do safety glasses and goggles differ from regular eyeglasses?
Safety eyewear must conform to a higher standard of impact resistance than regular eyeglasses, which optical professionals sometimes call "dress eyewear." This higher standard applies to both the lenses and the frames of safety glasses and goggles.
There are two kinds of safety glasses: prescription safety glasses and non-prescription (also called "plano" safety glasses.
Regardless of their size or the durability of the frame and lenses, regular prescription eyeglasses do not qualify as safety glasses unless they meet specific criteria.
In the United States, the federal government establishes safety guidelines for workplaces to decrease the risk of on-the-job injuries. The Occupational Safety and Health Administration (OSHA) within the U.S. Department of Labor oversees safety practices in the workplace and educational settings.
OSHA has adopted safety eyewear standards established by the American National Standards Institute (ANSI). This private, non-profit organization creates quality and safety standards for a wide variety of products.
The ANSI standard applying to eye safety includes several types of eye protection devices, including eyeglasses (both prescription and non-prescription), goggles, face shields, welding helmets and full-face respirators.
ANSI standards for safety eyewear
Updated ANSI safety eyewear standards include the following key features:
- For the basic impact tests, lenses are tested separately (not mounted in a frame). For the high impact classification, the frame and lenses are tested together as a unit.
- Non-prescription lenses used for high impact testing are considered to be structurally weaker than prescription lenses made of the same material; the prescription lenses are generally thicker.
- Thinner prescription safety lenses are now allowed if they meet the high impact testing requirements. (Previously, all prescription safety lenses had to have a minimum thickness of 3 mm, making them significantly thicker and heavier than regular eyeglass lenses.)
- Safety lenses now have two classifications of performance: basic impact and high impact.
- The "drop ball" test determines the basic impact safety classification for lenses. In this test, a one-inch diameter steel ball is dropped onto the lens from a height of 50 inches. To pass, the lens must not crack, chip or break. All glass safety lenses must undergo this test. For plastic safety lenses, however, only a statistical sample of a large batch of lenses needs to be tested.
- In high impact testing, a high-velocity test is performed by shooting a quarter-inch diameter steel ball at the lens at a speed of 150 feet per second. To pass, the lens must not crack, chip or break, and it must not become dislodged from the lens holder.
How to assess ratings of safety eyeglasses and goggles
Plus mark. To determine if a lens has passed the high-velocity test described above, look for the "+" mark that indicates its approval at high impact.
Top: This safety shield is found in hardware stores. It fits over smaller glasses but sometimes fogs up. Bottom: These safety glasses have side shields that don't offer quite as much protection, but they fogless.
This mark may be applied to any prescription lens of the same or greater thickness (at the thinnest point of the lens), made of the same material by the same manufacturer and with the same coating(s) applied.
"V" and "S" mark. Other lens markings that appear on safety lenses are "V" (indicating the lens is photochromic) and "S" (indicating the lens has a special tint). In some cases, a number may also be marked on a shaded safety lens to indicate how much the tint reduces light transmittance.
Shaded safety glasses for use when working with molten metal and in soldering, brazing, cutting and welding operations have tint densities that can range from 1.5 to 3.0 (mild to moderate shade for torch soldering) up to 10 to 14 (very dark shades for electric arc welding).
All safety lens markings must be permanent. If lenses do not meet the high impact standard, a warning label that can be removed only by the wearer must be affixed to prescription safety eyewear.
Testing of frames for safety eyeglasses and goggles
Frames for safety glasses are tested using the same criteria, whether they will be used in a basic impact or high impact applications. Frame tests include:
High mass impact. In this test, a one-inch diameter steel projectile weighing 17.6 ounces is dropped through a tube from a height of 50 inches onto a safety lens mounted in a frame. The frame is "worn" by an artificial head form. To pass, the frame must fully retain the lens, and no piece can become detached from the inner surface of the frame component that holds the lenses.
Durability. Safety frames must also pass a flammability-resistance test, a corrosion-resistance test and other durability tests.
This test involves shooting a quarter-inch steel ball at the lens and frame at a velocity of 150 feet per second from a distance of just under 10 inches. The test is repeated multiple times (each time with a new frame and lens) at different angles and positions of impact. The pass criteria are the same as for the high mass impact test.
How to assess standards for frames used in protective eyewear?
Non-prescription safety eyewear with non-removable lenses must be permanently marked with the manufacturer's trademark and "Z87" (basic impact) or "Z87+" (high impact) on either the front of the frame or on one temple.
Prescription safety frames must be permanently marked with the manufacturer's trademark and "Z87-2" on the front of the frame and both temples.
For complete information, you can purchase a copy of the ANSI Z87.1-2003 safety eyewear standard at the American National Standards Institute website.
What type of safety lenses do I need at work?
Your company's safety officer should determine which level of protection (basic impact or high impact) is needed for your job duties.
A few occupations requiring high impact protection in eyewear include:
- Plumbers and pipefitters
Some activities may require side shields, goggles or full-face protection. Employers and safety officers should consult OSHA to help determine which type of safety eyewear is most appropriate for different job positions. To learn more, visit the eye and face protection section of OSHA's website.
Check out Austgens WELDING
Also, the International Safety Equipment Association has published the "Eye and Face Protection Use and Selection Guide" as a companion to the ANSI Z87.1-2003 standard. You can purchase this guide from the organization's website.
If you work as an independent contractor, it's best to choose safety eyewear that has been rated at the high impact standard for all activities, just to be extra safe.
Which safety glasses are best for home use?
As with independent contractors, you should choose safety frames and lenses rated for high impact, for maximum protection.
If you don't require prescription lenses, or you wear contact lenses, you can purchase non-prescription safety eyewear from most hardware, building supply and sporting goods stores.
These safety glasses usually are made of lightweight polycarbonate for comfort and are available in attractive wrap-style frames. For the greatest protection value, choose models that have a high impact rating. (Look for the "Z87+" marking on the frame.)
Some models are even available with a bifocal reading segment in the bottom half of the lens if you are over age 40 and have presbyopia.
If you need prescription safety glasses, you must purchase these from an eye doctor or at an optical store with a valid eyeglass prescription written by a licensed eye care professional. Again, for the best protection, choose safety eyewear with a high impact rating. (The lenses will bear the manufacturer's trademark and a "+." The frame will be marked "Z87-2" on the inside of the front and temples.)
If you're age 40 and have a bifocal eyeglass prescription, safety-rated progressive lenses are available to help you see clearly at all distances without bothersome bifocal or trifocal lines in the lenses.
For mowing lawns and using a power trimmer or other power tools, choose a frame with side shields to protect you from flying particles or larger objects.
What types of safety glasses are best for sports?
The same recommendations for safety glasses for home use apply here. Also, consider purchasing an elastic band that attaches to the back of your temples, to keep your safety glasses securely on your head during active sports.
For sports, use comfortable, padded protective eyewear like these, from RecSpecs.
For hunting and sport shooting, always choose safety lenses that have a high impact rating. Consider a wrap-style frame with a non-shiny, matte finish and lenses with anti-reflective coating, to eliminate distracting reflections.
Safety frames with camouflage patterns are also available for hunting. If you need prescription safety glasses, make sure they have side shields for added eye protection.
For hunting, golfing and other sports that require acute vision, consider adding a sport-specific tint. Amber or yellow tints, for example, can enhance contrast for shooting.
Fish hooks are a major cause of sports-related eye injuries, so for fishing, choose a wrap-style frame and safety lenses with a polarized tint, to cut glare from the surface of the water. Eliminating the glare will not only let you see into the water more easily, but it will also make your eyes feel more comfortable.
Also, consider photochromic lenses for optimum vision and comfort in changing outdoor lighting conditions. An optician or other eye care professional can advise you as to which tints are best for your particular activities.
If you enjoy paintball, be aware that players without proper eye and head protection can sustain devastating injuries from paintball pellets fired from paintball guns. Head shields for paintball should combine eye and ear protection, and the shield should have a high impact safety rating. This is because some guns are capable of propelling paint pellets at speeds over 180 mph.
The most important rule for paintball is, never take your head shield off while you're in the playing area, even when a game has not yet begun.
Safety eyewear adheres to a high standard of impact protection and must meet specific criteria. The Occupational Safety and Health Administration (OSHA) and the American National Standards Institute (ANSI), a private, non-profit organization that creates quality and safety standards for a wide variety of products, define those criteria.
OSHA has adopted safety eyewear standards established by ANSI. The ANSI Z87.1 standard applies to eye safety and includes several types of eye protection devices:
- Eyeglasses (prescription and non-prescription)
- Face shields
- Welding helmets
- Full-face respirators
While there are different styles and features to choose from, all safety eyewear must, in addition to meeting ANSI standards, at a minimum, do the following:
- Fit properly to protect from hazards adequately
- Be comfortable with increasing chances of being worn consistently
Though available in a variety of frame colours and styles as well as lens shades and coatings, safety lenses and frame materials do not vary a great deal.
What are the materials of lens?
Safety lenses come in one of four different materials. Each meets or exceeds requirements for protecting eyes for at least some applications, but each has distinct features to consider for particular situations.
- Glass lenses – Not easily scratched but can be heavy and uncomfortable and tend to fog. Most prone to shattering, glass lenses are not safe to wear if impact is even a slight possibility.
- Polycarbonate lenses – Not as scratch resistant as glass but lightweight, better fog resistance, stronger than glass or plastic and therefore more impact resistant.
- NXT/Trivex – Many of the benefits of polycarbonate but better optical clarity, scratch resistance, and photochromic performance.
- Plutonite – Basically a purified carbonate, this proprietary material made by Oakley has superior clarity.
The most popular lens material for safety eyewear is polycarbonate, but Trivex lenses are becoming increasingly popular. Both offer 100% protection from UV light and are up to 10 times more impact-resistant than glass lenses.
Safety eyewear frames must be more durable and sturdy than frames for regular eyewear. Safety frames are made of different shatter-resistant materials depending on the application and sometimes include side shields. For example, sports eyewear usually have nylon frames because they are lightweight and flexible.
ANSI Z87.1 certified safety glasses undergo intensive testing to ensure they'll protect eyes as expected. Tests include
- Basic and high-impact for lenses and frames
- Exposure to non-ionizing radiation and chemicals
- Durability to flammables and corrosion
Regardless of what it's made of, be sure to check the specifications on any safety eyewear purchased to determine its level of protection. And remember, there is no safety eyewear optimal for every possible situation.
What makes safety glasses safe?
Employees are often required to wear safety eyewear in the course of their duties. In the past safety glasses were uncomfortable and bulky. Newer safety glasses are more comfortable to wear and can even be quite stylish.
OSHA requires workers to use appropriate PPE for any job which may pose a threat to a person's health. Eye or face protection shall be worn when workers could be exposed to flying debris, particles, or hazardous liquids. Any lenses or frames stamped with "ANSI Z87" will meet or exceed OSHA standards. The ANSI (American National Standards Institute) standard sets forth requirements for the design, construction, testing, and use of eye protection devices, including standards for impact and penetration resistance.
The standard designates that lenses will be divided into two protection levels, Basic Impact and High Impact as dictated by test criteria. Basic Impact lenses must pass the "drop ball" test; a one-inch diameter steel ball is dropped on the lens from 50 inches. High Impact lenses must pass "high velocity" testing. Here 1/4" steel balls are "shot" at velocities from 150 ft/sec for spectacles to 300 ft/sec for face shields. All eyewear frames, face shields, or crowns must comply with the High Impact requirement.
The impact protection level must be indicated on the device. Basic Impact spectacle lenses will have the manufacturer's mark and the Z87. High Impact spectacle lenses will also have a plus + sign following the Z87. (Note: Lenses/windows may have additional markings. Shaded lenses may have markings denoting a shade number such as 3.0, 5.0 etc… Special purpose lenses may be marked with "S". A variable tint lens may have a "V" marking.)
Side shield coverage, as part of the lens or as an individual component, has been increased rearward by 10-millimetres via a revised impact test procedure. While side protection in the form of wraparound lens, integral or attached component side shield devices is not mandated in this standard, it is highly recommended. Further, OSHA does require lateral protection on eye protection devices when a flying particle hazard may exist, and flying particle hazards are virtually always present in any industrial environment. All current non-prescription safety spectacles meet the requirements of OSHA and Z87.1 for side protection.
As you can see (yes, pun intended), the testing process is rigorous, and not all glasses are safety glasses. Employers must conduct a PPE assessment and then provide employees with the appropriate protection, including eyewear.
According to the Bureau of Labor Statistics, nearly three out of every five workers who suffered eye injuries were not wearing eye protection at the time of the accident. Wearing the correct safety eyewear for the task and the unique needs of the worker is important. Choosing protective eyewear is not as simple as just selecting a pair of safety glasses that meet the American National Standards Institute / International Safety Equipment Association (ANSI/ISEA) American National Standard for Occupational and Educational Personal Eye and Face Protection Devices Z87.1-2015. There are many features available for eyewear that can help ensure you have the best eyewear for the job you do. These features include lens coatings, lens tints/colours, welding filter shades and sizing.
Lens coatings can enhance the versatility (and even the life span) of a pair of safety glasses. These coatings are often available separately or in combination with other coatings for more functionality. One available type is an anti-scratch coating. This coating is designed to protect the lens when subjected to repeated impacts such as in grinding applications and other abrasive applications. It can also help extend the life of glasses when they are stored in conditions that may precipitate scratches. Some of these coatings are added on top of the standard lens while others are permanently bonded to the lens for even longer life.
Anti-fog coated lenses are another option to get the best performance out of safety glasses. Fogging is reported as the leading challenge workers face with safety eyewear. This type of lens coating helps reduce fogging in conditions such as cold-to-warm temperature transitions, humid environments, or when eye protection is worn with half-mask respirators. While an anti-fog coating is not 100%, fog proof, fogging can be minimized by getting a pair of eyewear with a fog-free lens that sits further away from the face and supplementing the lens coating by adding an anti-fog cleaner or spray.
Anti-static coatings are another option. These coatings help reduce the dust and particulate levels that stick to eyewear. They work well in environments where particulate levels are a concern or where dusts and particulates sticking to the lens would create a safety concern due to reduced visibility.
Mirror coatings come in a variety of colours and are used to help reduce glare. Slight mirror coatings on clear lenses are appropriate for indoor/outdoor glare reduction and workers going from light to dark conditions. Mirrored coatings on tinted lenses are for outdoor work in bright conditions where glare is a concern.
Lens Tints/Color Options
Polycarbonate lenses set the standard for today's safety eyewear and are available in many colours and tints. Selecting the correct coloured lens for the application is important to help get the best visual acuity.
Two terms are commonly used to aid in the selection of the correct lens colour and tint. The first is visible light transmittance (VLT). This is expressed as a percentage of available light that will pass through the lens. The second is the ultraviolet (UV) or infrared (IR) absorption. This is expressed as the percentage of UVA and UVB or IR radiation, and the lens will absorb up to a maximum wavelength in nanometers (nm). Both the VLT and UV/IR absorptions can vary by manufacturer, so always check the eyewear specifications to ensure you have what you need.
Clear lenses are appropriate for general indoor applications or outdoor applications with low light conditions.
Gray lenses are typically referred to as a sunglass-style tint. They are used in environments where bright light conditions and glare could cause eye fatigue. A grey lens provides good colour recognition but should not be used in low light conditions as it can block too much light.
Brown/bronze/espresso lenses are similar to grey lenses and can be used like a sunglass lens where bright light conditions or glare can cause eye fatigue. This lens should not be used in low light conditions. These lenses generally meet colour traffic signal recognition (TSR) requirements. TSR lenses are tinted lenses that minimize the alteration of real-world colours when viewed through the lens. These lenses are good for occupations such as motor vehicle operators and painters. The requirements for TSR lenses are located in ANSI Z80.3-2015, Non-Prescription Sunglasses and Fashion Eyewear Requirements.
Indoor/outdoor lenses are used for employees who go from light to dark conditions or need to reduce glare in indoor conditions due to harsh lighting. An indoor/outdoor lens is a clear lens with a slightly mirrored surface to reduce glare. This lens is not a photochromic (auto-darkening) lens.
Amber/yellow lenses are appropriate for low light conditions. This lens colour blocks blue light and gives optimum contrast. This lens should not be used at night as too much light is blocked.
Light blue lenses reduce glare, and the yellow tint has often given off by industrial/sodium vapour lighting. Yellow light can cause eyestrain and fatigue.
Vermillion/red lenses enhance contrast, while colour perception is unaffected. They are often used in inspection applications where colour acuity is needed.
Photochromic lenses transition from light to dark with changing light conditions. That means changing outdoor light conditions don't require changing eyewear.
Dark green lenses offer general-purpose protection from glare and UV. This tint should not be confused with a welding filter shade and will not provide adequate protection during soldering, torch blazing, cutting, gas welding or electric arc welding.
Welding Filter Shades
These filter shade lenses are designed specifically to be worn during soldering, torch blazing, cutting, gas welding and electric arc welding operations. They should never be worn as a general-purpose sunglass or for driving due to reduced light transmittance and the colour distortion associated with filter shades. Shaded lensed safety spectacles generally come in the shade 3.0 or shade 5.0.
The Occupational Safety and Health Administration (OSHA) standard on eye and face protection, 29 CFR 1910.133(a)(5), references the filter lenses that are appropriate based on the operation being performed. See Grainger's Quick Tips #109 for more information on selecting the appropriate welding shade. The ANSI/ISEA Z87.1-2015 Eye and Face Protection Selection Tool provides the most complete and up-to-date selection criteria for welding applications.
Most eyewear is made in a standard size to fit most faces. But in situations where a one-size-fits-all approach doesn't work, other sizes are often available to make wearing safety glasses comfortable. ANSI/ISEA Z87.1-2015 uses a European small and medium head form size for testing. And some styles are available with adjustable temples for a more customized fit.
OTG or over-the-glass eyewear is made to facilitate wearing safety glasses over prescription glasses. These glasses have a wider frame and lens to allow for most prescription eyewear to be worn underneath.
Wide safety glasses are made for people with wider facial features, while narrow styles are available for women and individuals with smaller or narrower faces.