The size of the water droplets that make up the mist helps determine how much cooling effect you'll be able to feel. As each little droplet evaporates, it cools the air immediately around it. Bigger droplets take longer to evaporate than smaller droplets. If they land on you before they've completely evaporated, you're wet. If you're in fairly dry air this can feel great as the water evaporates off of your skin. On the other hand, it can be uncomfortable in extremely humid weather, or if you just don't want to be wet. Also any water that doesn't evaporate must land on something. You'll need to make sure it doesn't puddle and that what it lands on is water-safe.