When talking about exposure to sunlight, you automatically think of sunscreen and/or hats, but have you ever thought that the sun also damages the eyes? Working outdoors means exposure to ultraviolet radiation from the sun, even on cloudy days.
Sun exposure will be different depending on the time of day, exposure time, shadows, and reflective surfaces such as water or sand on beaches or quarries. Safety sunglasses filter solar radiation, protecting your eyes from possible pathologies and facilitating comfort and visual perception of the environment.
How does optical radiation work?
Optical radiation is divided into ultraviolet radiation, visible radiation, and infrared radiation.
- Ultraviolet (UV) radiation: wavelength between 100 nanometres (nm) and 400 nm. It is divided into UVA, UVB, and UVC radiation.
- Visible radiation: wavelength between 380 nm and 780 nm.
- Infrared radiation (IR): wavelength between 780 nm and 1 mm. It is divided into IRA, IRB, and IRC.
Solar radiation includes UV radiation, visible radiation, and IR radiation, so you should protect yourself from it adequately. WHO recommends eye protection up to 400 nm, in other words, total protection against UV radiation.
How does the sun affect the eyes?
When sunlight passes through the atmosphere, ozone, water vapour, oxygen and CO2 absorb some of the UV radiation. But, another part of the UV radiation reaches the earth's surface, reaching our eyes and skin.
Depending on the type of radiation, some of the possible eye pathologies can be:
- Exposure to UV radiation: cataracts (increased opacity of the crystalline lens), photokeratitis (inflammation of the cornea), photo conjunctivitis (inflammation of the conjunctiva).
- Exposure to visible light: solar retinitis (leads to blind spots, which may be reversible or irreversible).
- Exposure to IR radiation: corneal and retinal burns, cataracts.
Professionals in agriculture, construction, gardening, lifeguards, and the sea are highly exposed to solar radiation. Depending on the ambient light and the individual's sensitivity to glare, different lenses are recommended.
In the case of protective eyewear, European standards test both the lenses and the frames. In this article, we talk about the lenses of safety sunglasses. As with all PPE, the CE or UKCA marking must always appear.
Difference between safety sunglasses and ordinary sunglasses
Regular sunglasses only protect against solar radiation.
- Clear tinted filters: low reduction of solar radiation (filters 0 and 1).
- Common tinting: good protection against solar radiation (filters 2 and 3).
- Special filters for extreme solar radiation at sea, in the mountains, or in the desert (filter 4, not suitable for driving).
The above filter classification for ordinary sunglasses is similar to the one for safety sunglasses. In addition to protecting against solar radiation, intense light, and UV radiation, safety sunglasses also protect against additional risks such as impact, dust, or splashes.
Lens marking on safety glasses
Safety sunglasses lenses always have the same elements as any other PPE for eye protection:
1. Protection code
2. Degree of protection
3. Manufacturer's identifier
4. Optical class
5. Mechanical strength and additional requirements
6. CE or UKCA marking
Protection code (from 2 to 6)
Type of radiation it protects against:
-UV radiation, filter with possible colour distortion (code 2).
- UV radiation, filter with good colour recognition (code 3).
- IR radiation (code 4)
- Solar radiation without specification for IR (code 5).
- Solar radiation with a specification for IR (code 6).
Degree of protection (from 1.2 to 16)
This is the level of protection offered for each type of radiation. The higher this number, the more the eyepiece will absorb the radiation and, in general, the lower the light transmission. Therefore, the lower the number, the higher the percentage of light transmission.
These first two sections ( protection code and degree of protection) separated by a hyphen make up the protection class of the spectacles.
Protection classes and tinting
The classification of the protection class (Protection Code - Protection Grade) of the filters of safety sunglasses is similar to that of ordinary sunglasses:
- Clear tinted filters: class 5 or 6 - 1, x.
- Medium filter, commonly tinted: class 5 or 6 - 2. Recommended for most situations.
- Dark filter: class 5 or 6 - 2,5.
- Very dark filter: 5 or 6 - 3.1. For direct observation of the sky, high mountains, bright water, sand, or quarries. Not recommended for driving.
- Extremely dark filter: 5 or 6 - 4.1. For very intense radiation. Not suitable for driving.
Manufacturer's identifier
The manufacturer of the safety glasses will always be identified in some way, either by a logo, name, letter, or abbreviation.
Optical class
Depending on the optical class, safety spectacles may be used for continuous work throughout the day (optical class 1), intermittent work (optical class 2) or occasional work, with a prohibition to wear them permanently (optical class 3).
Mechanical resistance and additional requirements
PPE may be fitted with protection against impact by high-velocity particles:
- S: minimum impact resistance (12 m/s)
- F: low-energy impacts (45 m/s)
- B: medium energy impacts (120 m/s)
- A: high energy impacts (190 m/s)
If the eyewear also protects against particle impact at extreme temperatures (-5 °C to 55 °C) it will appear FT, BT or AT.
Eye protection can also protect against electrical hazards (8), thermal hazards (9), and surface damage by fine particles - anti-scratch (K) or anti-fogging (N) treatment.
Types of lenses
- Polarised lenses prevent light from reflecting off objects and glare. They also enhance colours and promote visual comfort, reducing eyestrain. They are recommended for most outdoor work.
- Mirrored lenses reflect sunlight. They reduce glare and maintain visibility.
- Photochromic lenses adapt to light intensity, darkening in bright light or brightening in low light.
- Smoked lenses are ideal for avoiding bright light and glare when working outdoors. They prevent colour distortion and make it easier to see clearly while protecting your eyes.
- Yellow lenses filter out blue light and make it easier to see in fog, haze, and low light conditions. They are often used for hunting. They are not recommended for sun protection.
- Clear lenses are used for general work in low light intensity, i.e., indoors. They offer natural vision.
Remember: protecting your eyes from the sun is important both inside and outside the workplace, especially from UV radiation, to avoid future eye diseases. If you are looking for sunglasses for work, check out the eye protection section of Safeguru's online shop .
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