Mesh Masks for airsoft?

I bought a mesh mask a few days ago and my friend and I are going airsofting tomorrow at a place called tac city. Its a cqb field and the limit on the guns are 350 fps and they only allow people to use .20 bbs. I was wondering if it would be safe to use the mesh mask without any safety gles underneath it because the whole point of getting this mask was so it doesn't fog up. I sweat a lot so no matter what mask or lens i use it fogs up.