Obviously, the first step to cleaning up the squirrel feces in your attic is removing them. Remember to put on a mask of some sort and gloves for protection from infectious germs before you start cleaning up the mess. Spray disinfectant or a bleach-water mixture on the urine and droppings and let it soak for 5-10 minutes. The recommended concentration ratio of the bleach to water is 1-part bleach to 10 parts water. You will probably have to pick up the squirrel droppings one by one with your hand. Never touch the waste directly because of the germs that can be transmitted from squirrels to humans, particularly those zoonotic diseases that can be passed from squirrel to humans, such as leptospirosis and Salmonella. Use a paper towel or napkin to pick up the urine and droppings and dispose of them in the garbage immediately. If you have a filter vacuum, you should use it to collect the droppings quickly and easily. Just don’t forget you will need to sanitize the entire area afterwards. Just because you cleared all the droppings, doesn’t mean that the bacteria and fecal particles are all gone. Don’t forget to remove and replace items like insulation that may be contaminated.