What are Safety Glasses? Why are They Important?

Eye injuries are among the most common and lasting injuries in workplace accidents. Hazards such as dust, metal chips, chemical splashes, UV rays, and welding glare can lead to vision loss, permanent damage, and even blindness if proper protective eyewear is not used. Under Law No. 6331 on Occupational Health and Safety, employers are obliged to provide suitable eye protection to their employees based on the results of risk assessment.

The basic standard that safety glasses must meet is EN 166. This standard specifies requirements for frames, lenses, mechanical resistance, and optical quality. Additional protections for specific hazards are regulated by supplementary standards such as EN 169, EN 170, EN 171, and EN 172.

How to Read the EN 166 Lens Code?

The code on the lens and frame of safety glasses indicates which hazards the glasses have been tested against. Reading the code is the most reliable way to choose the right product.

Lens Code Sequence

Mechanical Strength Codes

Example lens code: "2C-1.2 1 F K N" → UV filtered clear lens, Optical class 1, Low energy impact resistance, anti-scratch + anti-fog coating.

Types of Safety Glasses

1. Dust and Debris Glasses

Used in environments with a risk of dust and flying particles, such as metalworking, construction, carpentry, and grinding. These glasses, equipped with polycarbonate lenses, lightweight frames, and sometimes side shields, must carry EN 166 F or B certification. Typical areas of use: automotive sub-industry, metal industry, paint-chemical industry.

2. Goggle (Sealed) Glasses

Glasses with a tight fit that are sealed against gas and liquid splashes. They are mandatory in chemical laboratories, paint shops, and any environment where acids/solvents are used. EN 170 standard should also be sought in addition to EN 166. For anti-fogging, lenses with an N (anti-fog) code should be preferred.

3. UV Protected Glasses — EN 170

Designed for outdoor workers exposed to sunlight and UV sources. EN 170 standard specifies the wavelength transmission limits of UV filters. The code "2C-1.2" indicates the UV protection level and light transmission. Suitable for construction, agriculture, road, and air transport work.

4. Industrial Sunglasses — EN 172

EN 172 covers industrial sunglasses with solar filters that provide protection against sunlight outdoors. Although they look like sunglasses, the optical quality and mechanical resistance requirements are much stricter. Suitable for port workers, road construction crews, and open-pit mine workers.

5. IR / Infrared Protected Glasses — EN 171

EN 171 regulates the performance of filter glasses that provide protection against infrared (IR) radiation. Mandatory for workers in foundries, glass factories, and high-temperature furnace environments. IR filter tints range from 1.2 to 10; they are selected according to the temperature and radiation intensity of the environment.

6. Welding Glasses — EN 169

Provides protection against intense light, UV, and IR radiation generated during welding operations. EN 169 standard defines welding filter tints. The higher the tint number, the darker the glasses and the stronger the protection against radiation.

EN 169 Welding Filter Tints

7. Over-the-Glasses (OTG)

Protective eyewear designed for workers who wear prescription glasses, worn over existing spectacles. Must comply with EN 166 standard and have sufficient internal clearance. OTG models that have been tested for comfort and fit should be preferred.

Lens Surface Coatings

What is Optical Class?

The optical class code (1, 2, or 3) on the lens indicates the degree of image distortion of the lens.

For long shifts, Optical Class 1 should always be preferred. It significantly reduces eye strain and headaches.

How to Choose the Right Safety Glasses?

1. Identify the hazard: Is it dust/debris, chemicals, UV/IR, or welding?
2. Check the mechanical strength code: At least F code for metal environments, B code for heavy industry is essential.
3. Select the optical class: Class 1 is mandatory for long-term use.
4. Assess coating needs: Hot environment → N (anti-fog), harsh environment → K (anti-scratch).
5. If you wear prescription glasses: Choose an OTG (over-the-glasses) model or a model with prescription adapters.
6. Verify CE mark and EN certification: Unapproved glasses do not provide legal protection.

Frequently Asked Questions

What is the difference between EN 166 and EN ISO 16321?

EN 166 is the eye protection standard that has been used in Europe for many years. EN ISO 16321 is the updated international version of EN 166, which came into force after 2022. For new product purchases, you should look for EN ISO 16321 certification; however, EN 166 certified products still retain their legal validity.

How long does anti-fog (N) coating last?

Anti-fog coatings wear off over time. Applying detergent or solvent to the lens rapidly destroys this coating. Only wipe with the manufacturer's recommended cleaner and use a dry cloth. Coating life typically ranges from 6 months to 2 years.

Which filter tint should I choose for welding?

It varies depending on the welding type and current value. For MIG/MAG, Tint 9–11 is generally suitable, for TIG Tint 10–12, and for oxyacetylene Tint 5. The table defined in EN 169 standard indicates which current value is suitable for which tint. Not choosing the correct tint leads to both eye strain and inadequate protection.

How often should safety glasses be replaced?

They should be replaced immediately if there are visible scratches, breaks, or lens haziness. Even if they appear undamaged, it is recommended to replace them every 1–2 years with intensive use. Glasses used in chemical environments should be checked more frequently due to the risk of chemical seepage.