What concentration of HTH is used to clean the gas mask lens?

• A. 0.5% HTH
• B. 1% HTH
• C. 2% HTH
• D. 5% HTH

Answer: (B)

The main idea here is using the right dilution of the cleaning solution to disinfect without harming the mask lens. High-Test Hypochlorite (HTH) is a chlorine-based disinfectant used to decontaminate gear, including lenses. Using a 1% solution provides enough chlorine to remove contaminants and disinfect the surface while staying gentle on the lens material, which is often glass or polycarbonate and can be sensitive to stronger chemicals. If you go higher than 1%, you risk hazing, etching, or coating damage on the lens, and you may leave behind chlorine residues that can irritate the eyes. If you go lower, the lens might not be cleaned or disinfected effectively. After applying the 1% solution, it’s important to rinse the lens thoroughly with clean water to remove any residue and then dry properly so the optical surface remains clear for safe use.