John Fischer, CSP, vice president of SVS Safety, ofen sees the problem of heat-induced eyewear fogging. (Defog It by Nanofilm photo)

Hot Weather and Safety Eyewear: A Closer Look at the Hazards

Even a worker in dry-as-a-bone Phoenix perspires more in the heat, which increases the moisture right behind the safety glasses and increases the prospect of fogging.

The calendar says summer's on the way. Temperatures already are beginning to spike in many parts of the country temperatures are already beginning to spike -- if they ever stopped. For safety professionals, that means it's the time of year to begin preparing plans to protect outdoor workers from heat stress.

The most common risks associated with high heat are well known: heat rash and cramps, to heat exhaustion and heat stroke. There’s one more that needs to be on the radar: Both OSHA's and CDC's educational materials advise that "Exposure to heat can also increase the risk of injuries because of … fogged-up safety glasses."

Two specific injury risks come to mind. First, when safety eyewear fogs up on a hot and steamy afternoon, workers may simply take it off, exposing themselves to a variety of hazards. Independent research confirms this instinct. A study reported in the scientific journal Accident Analysis and Prevention found that fogging is the number one vision-related barrier to wearing safety eyewear.

The second risk of fogged eyewear is impaired vision that can leave the outdoor worker open to injury while handling everyday tasks, a fact well understood by safety professionals who deal with high-heat indoor environments, such as utilities, metal fabrication, and paper mills. In fact, a survey among safety professionals found that 28 percent of them believed fogged eyewear had contributed to injuries in their own workplaces.

John Fischer, CSP, is vice president of SVS Safety, which assists companies with the development or enhancement of safety programs. He often sees the problem of heat-induced eyewear fogging. "I know of workplaces dealing with triple-digit temperatures and high humidity, but conditions don't have to be that extreme for fogging to raise a red flag for safety," he warned. "It's important to address it as a root cause to eyewear non-compliance and, more importantly, as a threat to worker safety."

Lost productivity is also a consideration when employees struggle with fogging. A conscientious person who removes, wipes, and re-dons safety eyewear multiple times during a shift can't be working up to potential.


Construction Workers See Problems
Construction workers suffer among the highest rate of eye injuries, according to the latest Bureau of Labor Statistics data.

More and more organizations are addressing the issue of fogging as a possible root cause of safety eyewear non-compliance. San Juan Construction, Inc. is a general contractor with projects throughout the U.S. and around the globe. The company's motto is "Safety first, people always."

Josh Hollingshead, project cost controller on a company job in North Carolina, said he is well aware of the fogging issue. "Heat and humidity are usually the problem. In the summer, it'll get up to 100 percent humidity sometimes," he said. Hollingshead's San Juan team found that providing an anti-fog coating that workers could apply when needed helped to prevent the problem.


Why Safety Eyewear Fogs More in Summer
Why does San Juan's construction team -- or any worker, for that matter -- encounter more fogging in summer? There are three reasons. Two of them are environmental issues -- heat and humidity. The third is a biological one -- human exertion. Here's how it works.

We're all familiar with the layer of water droplets that forms on the outside of a cold glass of lemonade sitting in muggy July heat. Because there's a temperature difference between the inner and outer surface, moisture in the air condenses onto the warmer surface -- the outside of the glass. The same process is at work with eyewear, except the droplets are tiny, creating fog.

In hot weather, the ambient temperature is already high, and the air between the wearer's face and the eyeglass lens can be even hotter, the way the air inside a closed car is hotter than the outside temperature. Then add the biological factor: The person laboring under the sun is likely to be generating increased body heat, so that temperature difference gets even higher. The conditions are ripe for fogging.

Next, add increased summer humidity. There's more water in the air waiting to be converted to fog, plus there’s the human component of perspiration. Even a worker in dry-as-a-bone Phoenix perspires more in the heat, which increases the moisture on the face, right behind the safety glasses, and increases the prospect of fogging.

The tighter the eyewear fits, the higher the risk.

Movement of air around the face and safety eyewear can help to lower the temperature and evaporate humidity, reducing the fogging risk. However, some of today's wraparound eyewear designs hug the face and reduce air flow. Workers who never experienced a fogging problem in spring and fall weather may see one develop. Goggles can present an even greater concern because their snug fit, a key to safety, may reduce ventilation.

That was the issue faced by Idaho Department of Transportation crews that paint the stripes on highways. Their closed goggles are crucial vision protection because right behind the work truck's paint jet is another jet spraying tiny glass beads that embed themselves in the wet paint to create a reflective surface. These miniature beads are so small they can infiltrate even the smallest vents in goggles. Dale Moore, electrician lead in the Lewiston office, had heard workers in safety meetings say their unvented goggles had a fogging problem. The cause? "Most of the time our weather is hot and dry, but with the closed goggles, the humidity inside the goggle is very high," said Moore. He said a worker-applied anti-fog treatment provided by the department solved the problem for his crew.


The Particular Challenge of Faceshields
Tactical officers often need to wear full-face and full-body gear. They are an extreme example of the problems of closed safety eyewear systems. In a pilot field test conducted with U.S. Coast Guard personnel working outdoors in south Florida heat and humidity, 77 percent of respondents affirmed a problem with fogging, with 87 percent of those affected reporting they had to remove their faceshields to clear them.

Workers donning two sets of eyewear can experience double the fogging problem because they have multiple optical surfaces trapping multiple layers of hot, moist air. This may include those wearing prescription glasses under safety faceshields, such as the ones first responders wear. Welders, who are required by regulation to wear both a faceshield and impact-resistant safety eyewear, may face an even greater challenge in the summer months.


How Can You Prepare?
The hot-weather injury risk of fogged-up safety glasses is a reality, as OSHA notes. For that reason, the topic needs to be integrated into heat stress safety planning. It should be incorporated as a part of an effective safety culture. Here are some key considerations:

  • Train for it. Just as you cover the symptoms of, and safety precautions for, heat stress, discuss fogging. Explain the potential for fogging problems. Review the organization’s safety eyewear policy and the injury risks of removing safety eyewear or working with fogged-up lenses. Inform workers of solutions available from the company.
  • Provide ways to prevent fogging. Consider offering workers anti-fog treatments or lenses. Think about adding additional styles of eyewear during the summer that could improve air flow.
  • Remember to address other barriers to safety eyewear compliance that might be aggravated by heat and humidity. Comfort matters; when nosepieces or temples get sweaty and slippery, they can slip off or chafe. A worker may solve the problem with a different eyewear design. Provide a strap; if glasses are removed during a break, they are less likely to be left on a bench or in the truck.
  • Be vigilant about compliance. If you see workers without eyewear, address it immediately and look into root causes.

This is a good time for indoor heat safety reviews, too. While organizations with outdoor workers are just now gearing up for the summer heat and humidity, others face the challenges year round. They include iron and steel foundries, confectioneries, chemical plants, and glassmakers, among others. The change of seasons is an opportune time for any organization to review its approach to safety eyewear and fogging.

The Isis Central Sugar Mill Company in Childers, Australia, is a good case study. The company mandates compulsory eye protection to help prevent dust and foreign-body eye injuries. "The need to wear safety eyewear has been established, and we all need clear vision to do our task," said Peter Whelan, Isis’ workplace health & safety officer. "If the glasses are removed due to lack of vision, the chances of permanent lack of vision suddenly become a potential reality.

"We started to run into problems with compliance in our manufacturing process as we use a significant amount of steam throughout the plant, which causes hot and humid environments," he added. In an effort to address the root cause, Isis began supplying workers an anti-fog treatment. When asked whether the safety strategy worked, Whelan affirmed, "There’s a very short answer to this one: yes."

In Isis' case, the lessons learned inside the factory about the relationship between safety eyewear non-compliance and humid-heat fogging migrated to its outdoor safety procedures, as well. "As the warmer tropical months approached, our outdoor workers were suffering the same fogging problems -- especially during night work," Whelan explained. Isis again found that offering an anti-fogging coating met the challenge.

Whether a work environment subjects employees to high heat and humidity for just three months a year or for all 365 days, the potential risks of fogged safety eyewear are documented and deserve careful consideration. Safety glasses aren't safe when they're fogged. Fogging has been shown to be a significant barrier to wearing safety eyewear, even in workplaces with mandatory policies. For the protection of your workforce, now is the time to make fogging a hot topic.

This article originally appeared in the March 2013 issue of Occupational Health & Safety.

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