In simple terms, fog is a cloud at ground level. It varies in density, thus having variable effects on visibility, depending on temperature and humidity levels. These conditions determine the speed at which fog forms and dissipates. The density of fog and the speed at which it forms and dissipates help assess risks and understand how to avoid them. 

Fog forms in highly humid environments. Water vapor in humid air attaches to dust and microscopic particles, forming suspended water droplets near the ground, creating a cloud. Depending on the cloud’s density, measured by visibility degree, it’s referred to as fog or mist. If visibility extends beyond one kilometer, it’s mist. Otherwise, it’s fog. 


Numerous sectors suffer significant financial losses due to fog. In oil and gas fields, on offshore platforms, and in mining operations, production losses from interruptions alone can amount to hundreds of thousands of dollars per day. Farms, construction sites, factories, and warehouses are also highly dangerous environments during foggy weather. In some cases, reduced visibility halts all activities, causing substantial losses for businesses and temporary workers often employed in these sectors. 


Similar to how fog clouds form in humid environments due to temperature differences between air and surfaces, fogging can occur on glasses due to temperature differences between the lenses and ambient air. This phenomenon can happen when a person transitions from a cold environment to a warmer one and vice versa. It’s particularly common in the oil and gas industry, the energy sector, warehouses, and other sectors involving frequent shifts between indoors and outdoors. 

Fogging can also occur in response to the heat emitted by your face contrasting with cooler ambient air. Air moisture condenses on the glass surface due to temperature differences. This is prevalent in agriculture, construction, and other sectors where manual workers exert physical effort and get warm. 

Several factors can increase the risk of fogging. Dirty and damaged lenses, for example, increase the surface area where condensation can occur, reinforcing the fogging effect, especially with outdated lenses. 

In highly humid environments, both indoors and outdoors, fogging can occur on glasses regardless of temperature differences. Prolonged exposure to cold can result in complete cooling of the lenses. Any exposure to higher temperatures will then cause persistent fogging despite efforts, such as wiping the lenses. Production sites in cold environments with high indoor temperatures are perfect examples: workers moving between outdoors and warm indoors expose themselves to a high risk of fog formation. 

Many individuals working in these environments face a dilemma. Wearing fogged glasses limits their visibility, reducing productivity and increasing the risk of accidents. Therefore, many choose to remove their protective glasses for better visibility. However, doing so exposes their eyes to other hazards such as light, heat, and airborne particles. Wearing fogged glasses poses other risks. 

When fog exposes workers to severe dangers, such as when using heavy equipment, it’s crucial to equip the lenses with both anti-fog and anti-scratch treatments. Anti-fog treatments include hydrophilic materials that absorb moisture and hydrophobic technologies that direct excess moisture to the sides of the lenses. Most protective glasses on the market have an anti-fog treatment on the inner surface and an anti-scratch treatment on the outer surface. However, this doesn’t cover all types of fog that may form. Other technologies, such as Bollé Safety’s Platinum treatment, ensure comprehensive protection against fog formation with both anti-fog and anti-scratch treatments on both sides of the lenses. 


Regardless of the type of glasses or goggles, several methods can limit or prevent fog formation on the lenses. The first basic rule is to keep glasses clean and ensure they are not too old or damaged. Next, ensure that the glasses are properly fitted and positioned on the face. Leave enough space between your face and the lenses to ensure good air circulation. This will help avoid temperature differences on both sides of the glasses. Similarly, avoid excessive heat on the face by wearing suitable clothing and exhaling away from the glasses. This can reduce temperature differences and limit resulting condensation. 

Certain substances can also be applied to the lenses to limit the risk of condensation. Anti-fog wipes, for example, contain special components preventing water droplet formation. The same result can be achieved by spreading a thin layer of soap or shaving cream on the lenses. However, the most readily available anti-fog substance is saliva. Breathe on the lenses or moisten them with saliva, spread it, and then wipe lightly. A residue effective enough to prevent condensation will remain on your lenses.