Paper corner guards are generally not suitable for use in humid environments. Paper products are susceptible to moisture and hygroscopicity, and can quickly lose strength and stability when they are exposed to high humidity or moisture. This means that if you use paper corner guards in a humid environment, they may become prone to warping, softening, disintegrating, or losing their protective function.

If you need to protect the corners of your items in wet environments, you may want to consider corner guards made from waterproof or moisture-resistant materials, such as plastic corner guards or metal corner guards. These materials are generally more durable and offer better protection in wet environments.

In short, appropriate corner protection materials should be selected according to the specific use environment to ensure that items are effectively protected.