Heat stress - the risks and costs of blurred vision

Sweat management as it relates to vision is an important and often overlooked component of heat stress. As temperatures rise, so does the amount of sweat that will drip into workers’ eyes and glasses. Blurred vision or stinging eyes can turn from annoying to dangerous in one blink of an eye. As with other safety equipment, the costs and risks associated with using inadequate protection can be great.

There are many considerations when selecting the best sweat management solution for your environment, but generally speaking, they fall into three main categories: function, safety and cost. As with most safety products, new cost-saving alternatives are available that address many of the age-old concerns. It’s important to evaluate the benefits and costs associated with the solution you choose and have enough information to make an informed decision.

Some of the most commonly used products are absorbent cellulose sponges, cotton bandanas or ‘skull caps’ made from technical fabrics, while hard-hat workers may use an absorbent terry-cloth ‘topper’ that attaches to the suspension system. New products exist that work by channelling sweat away from the eyes and glasses (similar to a rain gutter), rather than absorbing it.

Traditional products are designed to absorb sweat, and therefore are prone to saturation and allow sweat to drip into the eyes and glasses. Sweatbands that work by channelling sweat are not prone to saturation because they are made from a soft, non-absorbent, plastic, therefore they may be worn repeatedly and typically only require annual replacement. Plastic is easy to clean and sterilise by using bleach or other common cleaners. Technical fabrics may require the use of specialised cleaners in order to adequately remove oil, dirt and odour. Without special care, technical fabrics may not work as well to wick sweat.

Scientists that study sweat production have reported that athletes typically produce 1-3 L of sweat per hour, while in some instances they’ve recorded amounts as high as 6 L per hour. It’s easy to argue that workers can create similar sweat production, given the hot environments and the amount of clothing and PPE they wear. With sweat volumes like these, it’s very clear why hydration is so important and why absorbent sweatbands are ineffective.

Are you confident that the products you buy do not increase heat stress? Third-party thermal-imaging tests were conducted by Visionsafe with various sweatband products and proved what many people may already know. Heat is released from the top of the head, so it is advantageous to allow for good circulation. By covering the top of the head or forehead, the result is up to a 5% increase in surface-area temperature. The company concluded that, in order to reduce heat stress, it’s optimal to use sweatband products that cover as little surface area as possible. Because the plastic sweatbands were the lowest profile of the test group (1 cm tall), they simply trapped the least amount of heat and allowed for substantial air circulation.

In order for workers to be safe, clear vision is a must. Sweat dripping down the face and into the eyes is not only annoying, but downright dangerous. Stinging eyes and blurred vision can lead to a loss of focus and mistakes, therefore increasing the risk of injury. Work stoppage can occur frequently as workers stop to clear their eyes, wipe their face or clean their safety glasses.

It’s not uncommon for workers to wear PPE such as gloves, safety glasses, face mask or other protective clothing that inhibits them from safely wiping the sweat. For example, they might use their gloves to wipe their face or glasses and inadvertently introduce dust, debris or chemicals from the gloves into their eyes. To this point, health and safety managers have stated that a significant percentage of eye injuries result from workers introducing debris into their eyes while wiping sweat. If a contaminated glove, shirt or rag is used to clean safety glasses, they are more likely to become scratched, resulting in more frequent replacement. Workers may choose to remove their gloves or safety glasses, even remove their hard hat to wipe sweat from their eyes. In doing so, they may violate PPE compliance and expose their hands, eyes and head to risk of injury. To follow safety procedures they may have to move to a safe zone before they can remove their PPE and clear the sweat from their eyes. If the work environment calls for plastic suits, air packs or air hose, it may complicate the challenge further and extend the time needed to complete the sweat-wiping task. In some environments, such as those involving radiation, this effort may require a safety team or other personnel to assist the worker.

Heat stress will continue to be a challenge to workers, especially in hot or humid climates. Sweat management is an important component of dealing with the challenge. It would be advantageous for anyone responsible for the safety of workers in hot or humid conditions to re-evaluate the total performance and cost of traditional sweatband products and compare them to new options. If you can improve worker safety by offering a more effective solution and save money by doing so, why not start now?