In the summer months, outdoor workers in construction, landscaping, and utilities face a relentless enemy: mosquitoes and ticks. To protect themselves from West Nile virus and Lyme disease, workers aggressively apply bug spray containing DEET (N,N-Diethyl-meta-toluamide). They spray their arms, their necks, and their hard hat brims. And inadvertently, they destroy their safety glasses.
DEET is one of the most effective insect repellents ever invented, but it is also an extremely aggressive synthetic solvent. Most modern safety glasses and face shields are made of polycarbonate, a tough, impact-resistant plastic that is highly vulnerable to solvents.
When a worker sprays DEET near their face, or wipes sweat from their forehead with hands covered in bug spray, the DEET transfers to the polycarbonate lens. The solvent immediately begins to dissolve the anti-scratch and anti-fog coatings. It doesn't just smear; it chemically melts the top layer of the plastic, causing it to become cloudy, hazy, and permanently opaque.
This is not just an annoyance; it is a severe safety hazard. A worker with solvent-clouded safety glasses cannot see the trench edge, the swinging crane load, or the forklift backing up. They remove the glasses to see, and instantly lose their eye protection against flying debris. Worse, DEET can cause "crazing"-microscopic cracking of the polycarbonate. Crazed lenses shatter upon impact from a nail or grinding wheel, turning the protective lens into shrapnel.
The Maintenance Protocol: Never apply bug spray while wearing your safety glasses. Take the glasses off, apply the repellent, let it dry completely, and wash your hands before putting the glasses back on. If DEET gets on your lenses, immediately flush them with copious amounts of clean water-do not wipe them dry, as the DEET acts as a lubricant for the grit on the lens, causing deep scratches. If the lens has turned cloudy or has a smeared, melted appearance from chemical exposure, throw the glasses away. Your sight is too valuable to sacrifice for a mosquito bite.
