What You Need to Know About Anti-Fog Safety Glasses – Occupational Health and Safety

What You Need to Know About Anti-Fog Safety Glasses

Anti-fog measures are a critical part of keeping safety glasses safe.

• By Katherine Faulk
• Apr 01, 2021

Foggy lenses are something most glasses wearers have dealt with in the last year during the COVID-19 pandemic. Those who have always needed PPE for their jobs have been dealing with this issue for even longer. Fogging eyewear is a huge inconvenience and safety risk to those workers. In fact, fogging lenses are the number one reason workers remove or do not wear safety eyewear. Luckily, there is a solution in the form of anti-fog safety glasses. Before we dive into the science of anti-fog, it is important to understand the cause of fog itself.

What Causes Fogging?

Fogging lenses can be caused by several factors. It is first crucial to understand what the fog actually is. Regardless of its cause, fog is the result of water vapor that has condensed into fine droplets and collected on the lens. This is typically because the lens is cooler than the air around it. Why would this be? There are several potential reasons:

*Humidity. An abundance of warm, moist air is one of the most common causes of eyewear fog. Whether working outdoors or in purposefully humid environments, warm air will collide with the cooler eyewear and cause it to fog.

*Temperature change. Drastic changes in temperature are another common cause of fogging lenses. Going from a cold location such as a refrigerated unit or even just an air-conditioned indoor location to a warmer one will cause air to condense.

*Body heat. People working in warm environments or those exerting a large amount of physical force might also have to deal with fogging lenses due to their body increasing the temperature of the air around them. Sweat may also drop on eyewear and be treated similarly to fog.

*Face coverings. Some face coverings—especially when improperly worn—cause warm breath to go up into the orbital cavity. This has become increasingly more common as people wear masks to protect themselves from COVID-19.
While not a direct cause, washing anti-fog safety glasses can also increase fog risk, as water and soap can rub off some anti-fog coatings. For that reason, it is always important to follow manufacturers’ instructions for proper care of anti-fog safety glasses. Every manufacturer will have different rules on how to clean their lenses based on the type of anti-fog used as well as the material the eyewear is made of. Following these guidelines is the best way to maintain the integrity and longevity of your anti-fog eyewear.

This article originally appeared in the April 1, 2021 issue of Occupational Health & Safety.