The sun in Bolivia is incredibly strong. I've often wondered if the high altitude has something to do with it - at 8000 feet, are we really that much closer to the sun that it burns more fiercely? In any event, I have learned to be prepared when going outdoors. Though it is winter now in South America, it is still easy to get sunburned and dehydrated.
Be sure to bring a hat and sunscreen with you to Bolivia. Use them when you go outside. Drink lots of bottled water. Simple precautions will keep you healthy and happy.