Buying Safety Glasses – What are ANSI z87.1 and EN166?

Each year, hundreds of thousands of US workers risk injuring or severely damaging their eyes through work. When operating in environments that have hazards and present potentially dangerous situations as part of normal business, protective eyewear is essential. Safety glasses, safety goggles, spoggles and face shields are all required to protect worker’s eyes.

It is a responsibility shared between employer and employee to keep the workforce safe, but when it comes to eye protection, not all products are created equal.

What many people may not realise is that certain personal protective equipment will need to be designed to a specific standard. For specific hazards, and for certain levels of splash and dust protection, eyes need higher levels of protection. How can an employer know if they are buying the right protection for their workforce? The answer is to look out for the appropriate certification - In America, look for the American National Standards Institute (ANSI).

Two of the main regulations for safety glasses found on the market are ANSI z87.1 and EN166 - the European Standard.

Let’s take a closer look at what these standards mean, and why it's essential to bear these regulations in mind.

What is ANSI z87.1?

ANSI z87.1 oversees important marking of all occupational and educational personal eye and face protection devices in the US. By looking for ANSI markings, you’re making sure that you are finding the safest eyewear

ANSI z87 safety and health guidelines are set by the American National Standards Institute. The z87 certification helps to ensure eyewear is thoroughly tested for a variety of potentially dangerous situations. ANSI rated and tested goggles are designed to protect the wearer against chemical splashes, heavy impact, dust dispersal and particles, and even radiation. They can even protect you against intense heat and its potential impact.

How are Safety Glasses Tested Under ANSI z87.1?

Spoggles and safety eyewear tested under these regulations must pass a series of basic trials. These trials will analyse how effective goggles are when faced with:

● · Dust dispersal

● · Chemical / liquid spray or splashing

● · Blunt impact or force

These trials need to be intensive so that goggles (+spoggles) can be deemed safe for professional use. People who regularly work with sawing, drilling and grinding tools or harmful materials such as chemicals or bio products are required to wear ANSI rated eyewear for the utmost protection.

Impact Testing

Testing for impact is intricate. For example, impact testing will analyse how eyewear reacts to medium energy impact from a steel ball, to high energy impact from higher velocity attack with larger masses. Goggles will need to withstand blunt impact at speed as well as a considerable weight. You'll find a 'W+' on your goggle lens, or a simple '+' on your goggle arms if they've passed this test.

Splash Testing

Liquid and dust testing are similarly intensive. You will be able to tell whether or not safety eyewear has passed the ANSI trials for these hazards by checking for the following marking:

● · A 'D3' marking shows that goggles are resistant to liquid splashing.

● · A 'D4' marking shows that eyewear is protected against most dust.

● · A 'D5' marking applies to goggles which are resistant against the finest dust.

Note: goggles with prominent vents will not pass this test. Venting is important in terms of anti fog protection, maintaining clear vision. Whereas some vented models have passed this test with indirect venting systems, there is often a compromise between protection and fogging.

Don’t want to compromise? Take a look here

Other ANSI Tests

ANSI z87 regulations also check for ultraviolet or UV protection. Eyewear which has passed these tests will carry a 'U' and a number ranking their protection level. 'U5' or 'U6', for example, are highly-rated and highly protective

What is EN166?

Alongside ANSI z87.1, EN166 is a standard which applies to European safety models. European rated eye protection will be subject to similar tests as those under US rules, which means you can expect to purchase goggles which will protect you against dust, liquids and blunt impact.

However, markings on European-rated eyewear are, of course, a little different to those found with ANSI. European testing takes into account both the frames and lenses involved in goggle production, and you will be able to tell how protective your eyewear is by spotting certain codes and marks.

These markings will tell you how well your goggles performed in tests and make an informed decision about how well suited the safety eyewear is to your particular line of business.

What are the Main EN166 Markings?

It’s worth looking closely at what each of the markings mean before buying EN-rated international safety equipment. Here is a brief run-through:

Strength Under Impact

Frame strength is measured by a letter grade. You will see markings from S through F, B and A. S markings indicate that goggles will withstand small impacts - the lowest grade. A markings can withstand high-velocity impacts - the highest grade. The addition of the letter T indicates extreme heat resistance.

Dust Protection

You’ll need to check your frames for markings which show dust protection standards. Graded from 3 to 5. 3 means your goggles or spoggles have basic protection. 5 indicates resistance against fine, hazardous dust.

Radiation and Light Resistance

Your lenses will be marked from 2 to 6 on the UV scale, similar to the ANSI standard. UV6 indicates that you have 100% protection against glare, as well as infrared. Light resistance is also demonstrated through markings, with 3.1 being the most protective standard, and 1.2 being the lowest.

Optical Classes

EN166 also rates the quality of optics in safety eyewear. This is graded from 1 to 3, with 1 being optimum quality, and 3 being less efficient for constant visibility.


You should also check lenses for markings relating to coating. An N marking indicates that your eyewear has anti fog protection. K marking means your eyewear is protected against scratching


Both ANSI z87.1 and EN166 standards aim to show you how protective your safety eyewear is. It's a quick and easy way to find out whether or not the goggles you are considering are suitable for your line of work. Always make sure to check lenses and frames for markings.

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