I had been having a problem with my Olympus Tough camera lens fogging up on the inside, when out photographing fungi. This is because of the temperature differential when I set my camera into wet moss, or on the cold ground.
I asked around and it seemed the most promising way of combating this was to place the camera, with both doors open, in a sealed container with bags of silica gel.
I bought some silica gel and have been keeping my TG's in a sealed container with the two doors open.
I've taken the cameras out to use, since starting this, and then put them back into the container when I'm done.
So far there has been no fogging up of the lens, so I give this method a big thumbs up.
I bought silica gel packs made up for dive cameras. In the packet is a mixture of non-indicating gel and indicating gel. Indicating get goes green when it's saturated (mine has yet to go green) and then you put it in a low oven to dry it out and reuse again.
Silica Gel will continue to work until it has adsorbed 40% of its own weight.
How long it will last for depends on many variables such as: moisture sources within the contained space, from the packaging materials and external packaging permeability, how air tight the protection area is, the contents of the protection area, how often the protection area is opened and closed, the relative humidity of the surrounding area, the materials used in the construction of the storage area itself and so on.
The Indicating products start to change colour at 60% and steadily turn a dark green as saturation levels approach 100%. At that time you will need to replace the Silica Gel as it is fully adsorbed. Re-activate Silica Gel by drying it out in an oven at 70 degrees Celsius for approximately 120 minutes.