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      • Published 17 Jan 2023
      • Last Modified 12 Feb 2024
    • 8 min

    A Complete Guide to Safety Goggles & Glasses

    Understand why safety goggles and protective glasses are important and discover how to wear them correctly.

    This guide to protective glasses and safety goggles includes all the essential information that you need to know. We will cover what safety eyewear does, why this equipment is important, how to wear safety goggles and glasses correctly, and we will also explain the different ratings and grades.

    What are Safety Glasses and Goggles?

    Let’s start with the basics. Just what are safety goggles and glasses? In short, they are protective eyewear for use in hazardous environments - part of a broader category of products called Personal Protective Equipment, or PPE.

    Under Regulation 4 of the Personal Protective Equipment at Work Regulation 1992, it is mandatory to provide appropriate protective eyewear to employees who work in dangerous environments.

    Examples include:

    • Automotive
    • Steel manufacturing
    • Utilities
    • Food and beverage production

    Safety goggles and glasses, including the lenses, are made from scratch and impact-resistant polycarbonate - or acetate when the focus is on splash protection. Cheaper models may also contain standard plastic.

    What is the Difference Between Safety Goggles and Protective Glasses?

    The difference is straightforward.

    Protective Glasses

    Just like regular eyewear, protective glasses sit across the eyes, allowing air to enter around the edges. They are easy to put on and comfortable to wear with prescription lenses. They are also a good choice for situations where the primary hazard to the wearer’s eyes comes from the front.

    Safety Goggles

    Goggles, meanwhile, sit directly on the face and seal the wearer’s eyes, protecting them from splashes and dust. Safety goggles also provide more reliable protection from plastic and metal projectiles.

    There are three broad categories of safety eyewear - directly vented, non-vented, and indirectly vented.

    The first features a direct flow into the space below the lens, preventing condensation and providing a more comfortable fit for light tasks. By contrast, non-vented models are fully sealed, to provide maximum protection from dust, smoke, and liquid splashes.

    Indirectly-vented goggles are an attempt to provide the best of both worlds. The hooded or covered vent allows air under the lens to help prevent condensation but prevents the entry of splashed liquids or chemicals that could cause eye injuries.

    Browse All Safety Glasses

    Why are Safety Goggles So Important?

    Safety goggles and glasses protect the wearer’s eyes from flying debris, dust, smoke and corrosive chemicals following accidents or equipment failure. In other words, we wear eye protection to provide a crucial first line of defence for one of the most vulnerable organs in the body.

    Thousands of eye injuries occur in UK workplaces every year and around 20% of these are sufficiently serious to cause partial or complete blindness.

    How to Wear Safety Glasses Correctly

    Always inspect safety goggles and glasses before putting them on. Look for any dents, scratching, cracks or brittleness, and replace the item promptly if you do detect wear and tear. Safety eyewear is frequently exposed to harsh environments and can decay over time. Polycarbonate and acetate will also grow weaker over time as the material ages.

    Types of Safety Goggles and Eye Protection

    Different types of safety glasses and goggles are available, with each model designed for different tasks and working environments.

    When making a selection, consider the following key areas of risk:

    • Ultraviolet rays, infrared radiation, bright light sources (for example, welding torches)
    • Dangerous chemicals, liquids, gas or dust
    • High temperatures and hot objects or substances
    • Wood, metal or plastic debris and shrapnel (for example, grinding machines)
    • Electrical discharge (arcs) from short circuits and electrical faults

    Protection against such risks is indicated by a series of mandatory codes. See below for more information on these.

    Safety Goggles for Lab Work

    The main risk to eyes when working in a laboratory is chemical – for instance, hazardous chemicals or corrosive substances that have been spilt and splashed. Therefore, the best choice of protective eyewear for lab workers is full safety goggles with a protective seal. These should be worn whenever hazardous work is undertaken.

    Safety Goggles for Woodwork

    Dust is the major threat posed to eyes when woodworking. Grinding or sanding produces a fine spray of wood particles which can cause eye irritation - at the very least. Again, this means that full safety goggles are the best choice when working with wood.

    Safety Goggles for Construction

    Construction sites are dangerous places, filled with multiple health and safety risks. The best eye protection for use in such environments is goggles or glasses that provide reliable protection against smoke, dust particles, light exposure and electrical discharge.

    Safety Goggles for Cold Weather Conditions

    Safety goggles worn in low temperatures are prone to misting or fogging. To minimise this productivity-disrupting annoyance, look for models with an anti-mist chemical coating applied to the lens.

    Safety Goggle Frame and Lens Codes Explained

    Safety goggles and safety glasses are classified according to a European safety standard known as EN 166: 2001. All protective eyewear sold in Europe must comply with this code.

    Three separate standards - EN 170, 171 and 172 - define levels of protection against ultraviolet radiation, infrared radiation and sun glare respectively.

    Each set of standards defines a series of quality ratings, which are indicated by mandatory markings on the frames and lenses of each protective device. Assess the overall safety of the eyewear via the lowest rating displayed.

    Strength Ratings

    The strength of safety goggles is indicated with the following codes:

    • S : Resistant to a small object moving 12 metres per second
    • F : Resistant to a small object moving 45 metres per second
    • B : Resistant to a small object moving 120 metres per second
    • A : Resistant to a small object moving 190 metres per second
    • T : Resistant to impacts at extreme temperatures

    Frame Style and Protection Ratings

    The frame style and protective capabilities of safety goggles are indicated by the following codes:

    • 3 : Will protect against splashes (normally fully sealed goggles)
    • 4 : Protects against larger dust particles (over five microns)
    • 5 : Protects against smaller dust particles (under five microns)
    • 8 : Protects against electrical arcs (discharges) caused by a short circuit
    • 9 : Will protect against hot projectiles

    Radiation Protection Ratings

    The level of radiation protection provided by various models of safety goggles is indicated by the following codes:

    Safety Goggle Radiation Protection Rating



    Protection against ultraviolet light via a coloured light filter

    2C / 3

    Protection against ultraviolet light via a clear light filter


    Protection from infrared radiation


    Protection from sun glare


    Protection from sun glare and infrared radiation

    Light Transmission Ratings

    This rating indicates the percentage of protection provided against very bright lights such as welding torch flames. The lower the level of light transmission through the lenses, the greater the level of protection provided.

    Safety Goggle Light Transmission Rating

    Amount of Light Transmitted


    Between 74.4% and 100%


    Between 43.2% and 58.1%


    Between 17.8% and 29.1%


    Between 8% and 17.8%

    Optical Quality Ratings

    The optical quality rating of safety goggles indicates how frequently a pair of goggles should be worn to minimise the risk of eye strain.

    Safety Goggle Optical Quality Rating


    Class 1

    High quality - can be used freely on a regular basis

    Class 2

    Medium quality - fine for occasional use

    Class 3

    Low quality - only use on limited occasions

    Lens Property Ratings

    As the name suggests, lens ratings are used to indicate the strength and capabilities of these crucial components. As such, there is some overlap with the overall strength ratings listed above.

    • S : Protects against small objects moving at 12 metres per second
    • F : Protects against small objects moving at 45 metres per second
    • B : Protects against small objects moving at 120 metres per second
    • A : Protects against small objects moving at 190 metres per second
    • T : Resistant to extreme temperatures
    • N : Resistant to fogging or misting in cold temperatures
    • K : Resistant to scratches made by fine particles such as dust
    • 8 : Resistant to electrical discharge arcs caused by short circuit faults
    • 9 : Protects against hot projectiles


    Is it Safe to Wear Safety Glasses All Day?

    Yes. Wearing non-prescription safety eyewear all day will not damage your sight. However, wearing safety glasses or goggles for long periods while focusing intently can induce eye strain, something which is likely to affect your productivity. Eye strain and the accompanying headaches and blurred vision (especially risky in hazardous environments) are simply muscle fatigue.

    Like any product, you get what you pay for; cheaper, lower quality protective eyewear is more likely to induce eye strain than products designed with comfort in mind. This is because:

    • It may not fit correctly
    • It is more likely to scratch, forcing the wearer’s eyes to focus around the scratch
    • It could give a cloudy or slightly distorted view, again forcing the wearer’s eyes to work harder
    • It may be the wrong tint for the type of work being undertaken - another way in which the wearer’s eyes may be strained

    If you are engaged in a task which requires your close attention, it’s recommended to take regular breaks and give your eyes time to rest.

    Can Safety Glasses Be Worn Over Prescription Glasses?

    Yes, they can. Prescription safety glasses are available, although these can be costly. Wearing non-prescription safety glasses directly over prescription glasses is a less expensive option and this arrangement will also protect your prescription lenses from damage.

    If you plan to wear safety eyewear over prescription glasses, it is important to ensure you wear a pair that will fit comfortably. Some safety glass models are specifically designed to accommodate prescription eyewear so it’s important to do your research before making a purchase.

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