When the days get shorter and the temps get lower, many of us stop using sunscreen. But is that wise? According to researchers at Yale University, it takes just 15 minutes of sun exposure to damage the skin, regardless of cloudy days or crisper air. And that means it’s best to take the advice you have no doubt heard before: wear sunscreen or seek out shade when you’re outdoors, regardless of the season.

But that’s not the only thing that experts recommend. Here are some other questions answered by Yale dermatologists to help keep you protected from damaging UV radiation.

Mineral or Chemical Sunscreen?

The jury is still out on whether chemical sunscreen is completely safe for you, as the chemicals must seep into your skin in order to absorb the sun’s rays. That’s why many experts recommend mineral sunscreens instead, especially for those with sensitive skin or eczema.

How Often Do I Need to Reapply Sunscreen?

Most brands recommend reapplying sunscreen every two hours. But experts suggest this isn’t a hard and fast rule, and it varies by situation. For example, if you’re outside running or swimming, then chances are reapplying sunscreen every couple of hours is a good call. But, if you’ve been inside away from windows and direct light, you probably don’t need to apply another serving of sunscreen on before going outside.

Should I wait 15 minutes after applying sunscreen to go outside?

Most experts agree on this one: yes. Sunscreen needs to be absorbed into the skin before it can work, and that takes just a little bit of time. So, abide by the instruction on bottles and wait 15 to 20 minutes after applying sunscreen before hitting the pool, beach, or park.

Do you need sunscreen on cloudy days?

Absolutely. Unless you’re in the shade or completely avoiding the sun, sunscreen is still recommended. On any given day the sun can damage your skin so make sure to add sunscreen to your daily regimen.