 Gottheimer also says health agencies need to provide more guidance on how to use it as it can be confusing to navigate information online like how much to use and how frequently to apply it. Sunscreen should be applied daily, be reapplied every two hours when outside, and be at least SPF 30 or above and water resistant. A new report says an expert on Parkinson's disease visited the White House eight times over an eight-month period.